The 6mm GT (aka 6GT) cartridge was conceived as a “bigger Dasher” for PRS and NRL competition. The 6mm GT’s creators wanted 6mm Dasher accuracy and moderate recoil delivered via a cartridge with a slightly longer case body for better mag-feeding, longer neck for seating flexibility, and more moderate pressures. So far the 6GT has performed very well in PRS competition. Today’s story is a bit different — this is about an experiment — running a 6mm GT in an F-TR type rifle. Understand that, under current NRA rules, you may only shoot .223 Rem (5.56×45) or .308 Win (7.62×51), in official, sanctioned F-TR competition, but the 6GT is fine for F-Open. Mike McCasland wanted to see the potential of the cartridge for long-range target shooting, so he put a 6mm GT-chambered Bartlein barrel on a nice custom rifle with McMillan XIT stock and Kelbly F-Class Panda action. The results were impressive.
6mm GT — New Cartridge with Multi-Discipline Potential
Story by Mike McCasland, Texas Precision
The 6mm GT began garnering attention within PRS circles in early 2019. It promised to shoot 105-110gr 6mm bullets at 2950-3000 FPS, yet not suffer from mag-feed issues sometimes found with 6mmBR variants such as the 6 Dasher, 6BRX, and 6BRA. Moreover, since it burned less powder, the 6mm GT promised increased barrel life compared to the 6mm Creedmoor or 6XC. The 6mm GT case size should still work with the accurate powders in the Varget burn-range. I found the 6GT also worked great with H4350.
As someone who aspired to building a repeater and jumping into the PRS game, and had a spare F-TR rifle sitting around, I thought it would be fun to build up a 6mm GT to see if there was any merit to the hype. My smith, Wes Ripley of RIP Precision in Texas, builds a lot of PRS rigs, and already had the reamer on hand (a 0.120″ freebore variant).
Whidden Gunworks had some 6mm GT FL bushing die kits in stock, so I figured why not see what all the fuss was about? At the very least I could play around with the 6mm GT in F-Open Class at local club matches to see how it compared to the 6BRA, 6 Dasher, and other popular 6mm cartridges.
Click image to see video comparison of multiple 6mm cartridges by Quarter Minute Magnums.
How the Project Got Started with Backup F-TR Rig
My 6mm GT build really started as a project spawned purely from COVID-19 Isolation boredom. This rifle primarily serves as a backup F-TR gun, and it had been relegated to performing some load development on .308 barrels, so I could spin new ones on my main match rifle. The only problem was, I had run out of .308 barrels that needed load development. So, I basically had an ideal test platform just collecting dust in the safe. All I needed was a 6mm GT-chambered barrel, since (like the 6mmBR) the 6mm GT works in a short action with a .308 Win-sized bolt-face.
6mm GT Rifle Specifications:
Action: Kelbly Panda F-Class SA RB/RP
Stock: McMillan XIT with RAD 2A
Barrel: 30″ 5R Bartlein 1:7.5″-Twist, HV Contour
Scope: Vortex Golden Eagle 15-60x52mm
Trigger: Jewell Benchrest, about 2 ounces
Bipod: Phoenix Precision
Mike McCasland reports: “I have used both Hornady and Alpha brass in this rifle and haven’t noticed much difference between the two. I will say that my batch of Alpha brass was slightly softer than Alpha brass I’ve used in other calibers; you could feel a difference when neck turning cases. I’m unsure if that’s a batch issue, or something specific to their 6mm GT brass as a whole. As far as performance, there was little discernable difference. Oddly enough, the Hornady brass seemed to have slightly less case capacity than the Alpha; with most other cartridges it’s the other way around.”
In this video, George Gardner of GA Precision talks about the 6mm GT cartridge which he helped develop.
POWDERS — The 6mm GT was designed with Hodgdon Varget in mind, and that popular powder works exceedingly well in this platform. That said, the 6mm GT can work with a wide variety of powders, some yielding better performance than Varget.
I’ve tried a multitude of powders during my initial 6mm GT load development: Varget, Shooters World Precision, RL16, VV N140, H4350, and RL-15 to name a few. In my barrel, Hodgdon H4350 seems to deliver the best velocity/accuracy combination. SD and ES also seemed to be the lowest with H4350.
Load Development for the 6mm GT — Many Powders Tested
BULLETS — The most common 0.120″ freebore chamber allows for the majority of high-BC 6mm projectiles found in both F-Class and PRS. I had good luck with the pointed 107gr Sierra Match Kings (SMK), as well as the 110gr Hornady A-Tips in my rifle. For those looking to run the heavier 112-115 grain 6mm offerings, I believe GAP designed a 0.160″ freebore reamer that gets those bullets out of the neck/shoulder junction. Shown below is the 0.120″ freebore JGS reamer print:
SUMMARY — Good Cartridge with Much Potential
Generally speaking, I think the 6mm GT is a good little round. Some may not subscribe to this theory, but I believe some cartridges are inherently easier to tune than others. I’m not sure the 6mm GT is as easy-to-tune as a 6mmBR, 6 Dasher, or 6 BRA, but I don’t think it lags that far behind.
With relatively little trouble, I was able to find loads with both Varget and H4350 that would consistently shoot very well — 0.2 to 0.3 MOA. Moreover, I found the 6GT cartridge lives up to the velocity claims made by G.A. Precision. I was easily able to push the 110gr A-Tips to 2950 FPS, and the 107gr SMKs to low 3000 FPS range without any pressure signs, or unnecessary wear and tear on the brass.
As a fun test, I ran my 6mm GT rifle in a local 1000-yard F-Class match with the 110gr A-Tips, just to see just how well they would perform. Although wind conditions of the day and some E-Target issues prevented my 6mm GT rig from getting the better of the larger 7mm and .30-Cal rifles, the 6mm GT proved itself an accurate little round at distance. Here is a 1000-yard ShotMarker target:
After putting several hundred rounds through my 6mm GT rifle, I anticipate building another 6GT on a repeater action to give PRS a try. I think if you are looking for a dual-purpose rifle that can run tactical matches (with 100% feeding reliability), and can also be used for mid-range, F-Open Class competition, the 6mm GT would be a very good option.
About the author, Mike McCasland:
Mike McCasland is an avid shooter who competes regularly in F-Class matches. Based in Texas, Mike is the creator of the Texas Precision YouTube Channel. There you’ll find many videos covering reloading, gun projects, and marksmanship. Mike has done some notable product reviews including a comparison test of Micrometer Competition Seating Dies. To access Mike’s YouTube Channel, CLICK HERE.
The question of barrel break-in is controversial. Some folks advocate an elaborate, lengthy cycle of shooting and brushing, repeated many times — one shot and clean, two shots and clean and so on. This, it is argued, helps barrels foul less and shoot more accurately. Others say minimal break-in, with patching and brushing after 10-15 rounds, is all you need. Still others contend that break-in procedures are a total waste of time and ammo — you should just load and shoot, and clean as you would normally.
We doubt if there will ever be real agreement among shooters concerning barrel break-in procedures. And one must remember that the appropriate break-in procedure might be quite different for a factory barrel vs. a custom hand-lapped barrel. This Editor has found that his very best custom barrels shot great right from the start, with no special break-in, other than wet patches at 5, 10, and 15 rounds. That said, I’ve seen some factory barrels that seemed to benefit from more elaborate break-in rituals.
What’s the best barrel break-in procedure? Eric Mayer of Varminter.com decided to ask the experts. Eric interviewed representatives of three leading barrel manufacturers: Krieger, Lothar-Walther, and Shilen. He recorded their responses on this video. In order of appearance, the three experts are:
Shilen, Krieger, and Walther Experts Talk about Barrel Break-in
Do I Need to Break-In a New Rifle Barrel?
Eric Mayer of Varminter.com says: “That is a simple question, [but it] does not necessarily have a simple answer. Instead of me repeating my own beliefs, and practices, on breaking-in a new rifle barrel, I decided to answer this one a bit differently. While we were at the 2016 SHOT Show, we tracked down three of the biggest, and most popular, custom barrel makers in the world, and asked them what they recommend to anyone buying their barrels, and why they recommend those procedures. We asked the question, and let the camera run!” Launch the video above to hear the answers — some of which may surprise you.
Barrel Break-in — Initial Inspection and Cleaning
This video explains that you should always inspect and clean the bore of your barrel before sending rounds through it. There may be remnants of the production process, such as lapping residues, that you’ll want to get out of the bore. We’ve even seen a few tiny metal pieces in some factory barrels. And it’s always wise to borescope a new barrel to see if there are visible defects in the rifling such as lands that have flawed edges — we’ve seen that on some cheaper barrels.
Barrel Break-In — Ian Klemm’s Surprising Observations
Here’s a 10-minute Vortex Nation interview with Ian Klemm. Ian, a 4-Time F-TR National Champion is one of America’s best long-range shooters. In this video, Ian explains his approach to barrel break-in, which may surprise you. Does barrel break-in even matter? Conventional wisdom says “Yes” and perhaps there’s some truth to that, but Ian argues that break-in is NOT nearly as important as the internet wants you to believe. Ian believes that you don’t need to waste a ton of time/ammo to get your barrel ready to shoot extremely accurately. This may be particularly true with premium hand-lapped custom barrels.
Barrel Break-In Procedures with Keith Glasscock
Keith Glasscock is also one of America’s greatest F-Class shooters who has finished second at the Nationals multiple times. Keith is also a highly-respected wind coach who has a popular YouTube video channel, Winning in the Wind. In this video, Keith explains his procedure for breaking-in his match barrels. He starts by bore-scoping the barrel and cleaning it. If he finds some burrs he may use some JB Bore Paste, a patch, and a worn brush and “give that throat a little scrub” (See 1:30 time-mark). He used different stroke lengths to avoid putting a “step” in the throat. When he’s satisfied he goes to the range. He fires the first five rounds, then cleans. He then fires quite a few rounds before cleaning the barrel again and beginning load development (See 8:25 time-mark).
General Barrel Break-in Procedures Recommended by Brownells
Brownells Gun Techs Steve Ostrem and Caleb Savant tackle a thorny topic: breaking in a new barrel. What IS breaking-in a barrel? And WHY do it? The rifling of a freshly machined barrel has microscopic burrs and sharp edges. “Breaking-in” is the process of putting bullets down the bore to smooth out those rough spots. The goal is to round down the sharp edges so they’re not stripping copper off a bullet as it travels the bore, which leads to fouling that leads to reduced accuracy and inconsistent groups. In a very minor way, you’re actually lapping the barrel. The breaking-in process works best on cut-rifled and button-rifled barrels. Cold hammer-forged, chrome-lined, or nitrided barrels — such as commonly found on AR-15s — may not benefit much from the process. Pistol barrels really don’t need to be broken in because larger-diameter bullets are not so much affected by tiny variations in the bore. Likewise, break-in is more helpful for a .17, .20, or .22 caliber rifle than a .45 caliber rifle.
George Gardner of G.A. Precision Talks About Barrel Break-In
G.A. Precision’s George Gardner is a leading figure in the PRS/NRL world. In this video, George makes the valid point that not all barrels require the same amount of break-in. George says some barrels require very little break-in, while others benefit from a more elaborate break-in process that helps reduce future copper and powder fouling. He calls this “seasoning” the barrel so it fouls less. For a typical barrel, George’s recommended process (4:25 time-mark) starts with one shot, then clean for three one-round cycles. This is followed by three shots then clean, with repeat 3-shot cycles if need. For cleaning George prefers nylon brushes (5:50 time-mark). NOTE: George also makes a very important point — you MUST swab the chamber and get it dry between cleaning cycles (5:30 time-mark).
For today’s Sunday GunDay story, we feature highlights from two in-depth reports on rifles built around the relatively new 6GT cartridge (also known as the “6mm GT”). Developed by George Gardner (G.A. Precision) and Tom Jacobs (Vapor Trail), the 6GT was designed to feed well from magazines, be more efficient than the 6mm Creedmoor, and offer outstanding accuracy. It is just enough bigger than the 6mmBR or 6 Dasher so it feeds better. But it retains many of the qualities of the 6mmBR (high efficiency and outstanding accuracy). Burning significantly less powder than the 6mm Creedmoor, the 6GT is a bit less expensive to shoot, and should, theoretically at least, deliver better barrel life.
“The [6GT] is a more predictable and barrel-friendly cartridge than the 6mm Creedmoor. It can utilize the accurate and forgiving powders of the 6BR, has fantastic accuracy, and due to its shoulder angle and case length, it doesn’t suffer from feeding issues.” — PewPewTactical.com
We should say that the 6 Dasher has been used very successfully in PRS/NRL competition, with some aftermarket magazine accessories. For this reason, if you already shoot a 6 Dasher, moving to a 6GT may not be worth the cost of new dies and new brass. A.J. Deysel, writing for LoadDevelopment.com, writes:
“The longer case of the 6mm GT means it feeds as reliably from a magazine as a 6mm Creedmoor, and offers slightly higher powder capacity and in turn velocities than the 6mmBR variants, whilst still being able to use the same accurate and forgiving propellants.
You will also find many competitive and average Joes shooting 6mmBR and 6mm Dashers with a Primal Rights or some other mag conversion kit, having very few if any mag-feed issues at all, so that pretty much also nullifies the need to move away from those [chamberings] if you already own one of those or the reloading equipment for it.” — LoadDevelopment.com
Part I: The 6GT Cartridge for Precision Rifle Competition
Report by Vu Pham
I was ready to build a 6 Dasher when I saw a lot of buzz… about a new caliber George Gardner (Owner of G.A. Precision) and Tom Jacobs (Owner of Vapor Trail Bullets) designed, the 6GT. After some research and talking to George, I ditched the 6mm Dasher build and had GA Precision build me a 6GT on a GAP Templar action I already had in the safe. The reasons to try the 6GT in a new PRS-style rig were as follows:
1. Push a 110-115 grain class bullet at 2880-2930 FPS safely in the Sacramento heat.
2. Achieve a load that is reliable and predictable. The caliber must be easy-to-tune and predictable from barrel to barrel. I don’t want to spend weeks developing a new load each time I spin on a fresh barrel.
3. Be able to run the same mag in all my guns without having to tweak or use mag kits. The round must feed from AICS and AW magazines without major tweaking or hiccups.
4. Get good barrel life. The barrel needs to go 2200-2500 rounds with match-grade reliability and accuracy.
5. Have a competitive cartridge with the least possible recoil without sacrificing too much performance down range, compared to bigger options like the 6mm Creedmoor.
6GT feeding from un-modified magazines has been flawless in all the rifles we tested. The 6GT feeds so well, I sometimes have to do a press check to ensure there is a round in the chamber.
On paper the 6GT seemed like the perfect cartridge for PRS- and NRL-style competition. It has the low recoil of a 6 Dasher, with good feeding and mag compatibility. With the 6GT, a competitor can push 105gr bullets at 3000+ FPS or run heavier bullets at 2800-2900+ FPS.
Knowing that I would initially have to make my own 6GT brass and do quite a bit of load development, I enlisted the help of Dan Bertocchini with CS Tactical. Dan has a lot more experience with wildcats and is the man when it comes to this type of data gathering. He has been running a 6 Dasher for a few years so I was curious how he would compare the 6GT to his 6 Dasher.
Quick Summary: “I am really digging the 6GT and the capabilities it offers. It can launch 103gr Vapor Trails at 3000+ FPS or lob heavy 115gr DTACs in the low-to-mid 2900s comfortably. I think we will see this cartridge go mainstream in PRS/NRL-style competition in 2020.” — Vu Pham
The new 6GT Cartridge Was Tested in Three (3) Tactical Rifles:
Rifle 1: Vu’s 6GT 1.0
Builder: GA Precision
Action: Left Hand GAP Templar (large firing pin)
Barrel: Bartlein 7.7 Twist finished at 26″ with a 419 Hellfire Brake
Stock: KMW Sentinel
Optic: Vortex Razor Gen II 4.5-27x56mm EBR-7C MRAD
Bi-Pod: Harris
Trigger: Timney Calvin Elite
Magazines: AICS and AW
Support Bag: Wiebad Fortune Cookie
Rifle 2: Vu’s 6GT 2.0
Builder: Rubicon Precision
Action: Impact Precision 737
Barrel: Bartlein 7.0 Twist finished at 27″ with a 419 Hellfire Brake
Stock: XLR Industries Envy Chassis
Optic: Vortex Razor Gen II 4.5-27x56mm EBR-7C MRAD
Bi-Pod: Harris with Henderson Arca adapter
Trigger: Trigger Tech Diamond
Magazines: AICS and AW
Support Bag: Wiebad Fortune Cookie
Rifle 3: Dan’s 6GT
Builder: CS Tactical
Chambered by: Rubicon Precision
Action: Lone Peak Arms Fusion
Barrel: Proof 7.0 Twist finished at 28″ with a Muzzle Brake and More Brake
Stock: XLR Industries Envy Chassis
Optic: Minox ZP5 5-25x56mm MR4
Bi-Pod: Arca Cyke Pod (PRS)
Trigger: Trigger Tech Diamond
Magazines: MDT
Support Bag: Armageddon Gear OG Game Changer, Waxed Canvas
Alpha Munitions Pre-Production 6GT Brass George Gardner was kind enough to send us 50 pieces of Pre-Production Alpha 6GT brass for preliminary testing. Like the cases I formed from 6.5×47 Lapua brass, the Alpha 6GT brass will use a small rifle primer. Purchased direct from Alpha Munitions, 6GT brass is now $1.30 per case, which is comparable with Lapua 6mm Creedmoor brass, currently $120.99/100 at Grafs.com.
The major difference between 6.5×47 Lapua-formed brass and Alpha 6GT brass is the case capacity. Alpha 6GT brass has 1.5 to 1.7 grains more case capacity. When a piece of 6.5×47 Lapua brass is formed into a 6GT, the walls of the case now become the shoulder and part of the neck. In a normal piece of brass, the shoulder and neck are typically thinner because of the thickness of the brass tapering from the body to neck.
While the cartridge design was optimized for Hodgdon Varget, the extra case capacity of the Alpha 6GT brass opens the door to Hodgdon H4350 (my favorite powder) and Alliant Reloder 16.
Test Results with Alpha Munitions 6GT Brass
Initial test results were as expected from a premium brass-maker. Dan and I both got excellent Standard Deviations and Extreme Spreads over my MagnetoSpeed V3 and his LabRadar. This string below was with 112gr Barnes Match Burners and 33.8 grains of Varget. Can’t complain about a 3 FPS Extreme Spread!
Yes, H4350 Works with the Alpha Munitions Brass
Personally, I prefer running Alpha 6GT brass with H4350 rather than Varget pushing a heavier bullet. H4350 burns slower and cleaner which should equate to better barrel life. The Lapua-formed 6GT cases just do not have the capacity to reach the cartridge’s full capability with the slower burning powders.
Is the 6GT cartridge accurate? Definitely. Here is a 5-shot group at 600 yards shot by Dan. This was Alpha 6GT brass, with Hodgdon H4350 pushing Barnes 112gr Match Burner bullets.
PART II — 6GT Load Development with Multiple Powders
This text is taken from a full report by Mike McCasland on his 6GT (aka “6mm GT”) bolt action rifle. This rig was designed for general use, not just for PRS/NRL matches. In his 6GT rifle, Mike tested multiple powders including Varget, H4350, Reloder 16, Reloder 15, Shooters World Precision, and Vihtavuori N140. For more details, CLICK HERE for full report.
About the 6mm GT Cartridge
BRASS — The first thing you’ll find is cartridge brass choices for the 6 GT are rather limited currently. At present, the only commercial options are Hornady and Alpha Munitions. For the die-hard Lapua fans, you can technically make 6mm GT brass from 6.5×47 Lapua, however that process is very labor-intensive.
I have used both Hornady and Alpha brass in this rifle and haven’t noticed much difference between the two. I will say that my batch of Alpha brass was slightly softer than Alpha brass I’ve used in other calibers; you could feel a difference when neck turning cases. I’m unsure if that’s a batch issue, or something specific to their 6mm GT brass as a whole. As far as performance, there was little discernable difference. Oddly enough, the Hornady brass seemed to have slightly less case capacity than the Alpha; with most other cartridges it’s the other way around.
POWDERS — The 6mm GT was designed with Hodgdon Varget in mind, and that popular powder works exceedingly well in this platform. That said, the 6mm GT can work with a wide variety of powders, some yielding better performance than Varget.
I’ve tried a multitude of powders during my initial 6mm GT load development: Varget, Shooters World Precision, RL16, VV N140, H4350, and RL-15 to name a few. In my barrel, Hodgdon H4350 seems to deliver the best velocity/accuracy combination. SD and ES also seemed to be the lowest with H4350.
Load Development for the 6mm GT — Many Powders Tested
BULLETS — The most common 0.120″ freebore chamber allows for the majority of high-BC 6mm projectiles found in both F-Class and PRS. I had good luck with the pointed 107gr Sierra Match Kings (SMK), as well as the 110gr Hornady A-Tips in my rifle. For those looking to run the heavier 112-115 grain 6mm offerings, I believe GAP designed a 0.160″ freebore reamer that gets those bullets out of the neck/shoulder junction. Shown below is the 0.120″ freebore JGS reamer print:
SUMMARY — Good Cartridge with Much Potential
Generally speaking, I think the 6mm GT is a good little round. Some may not subscribe to this theory, but I believe some cartridges are inherently easier to tune than others. I’m not sure the 6mm GT is as easy-to-tune as a 6mmBR, 6 Dasher, or 6 BRA, but I don’t think it lags that far behind.
With relatively little trouble, I was able to find loads with both Varget and H4350 that would consistently shoot very well — 0.2 to 0.3 MOA. Moreover, I found the 6GT cartridge lives up to the velocity claims made by G.A. Precision. I was easily able to push the 110gr A-Tips to 2950 FPS, and the 107gr SMKs to low 3000 FPS range without any pressure signs, or unnecessary wear and tear on the brass.
As a fun test, I ran my 6mm GT rifle in a local 1000-yard F-Class match with the 110gr A-Tips, just to see just how well they would perform. Although wind conditions of the day and some E-Target issues prevented my 6mm GT rig from getting the better of the larger 7mm and .30-Cal rifles, the 6mm GT proved itself an accurate little round at distance. Here is a 1000-yard ShotMarker target:
After putting several hundred rounds through my 6mm GT rifle, I anticipate building another 6GT on a repeater action to give PRS a try. I think if you are looking for a dual-purpose rifle that can run tactical matches (with 100% feeding reliability), and can also be used for mid-range, F-Open Class competition, the 6mm GT would be a very good option.
About the author, Mike McCasland:
Mike McCasland is an avid shooter who competes regularly in F-Class matches. Based in Texas, Mike is the creator of the Texas Precision YouTube Channel. There you’ll find many videos covering reloading, gun projects, and marksmanship. Mike has done some notable product reviews including a comparison test of Micrometer Competition Seating Dies. To access Mike’s YouTube Channel, CLICK HERE.
The question of barrel break-in is controversial. Some folks advocate an elaborate, lengthy cycle of shooting and brushing, repeated many times — one shot and clean, two shots and clean and so on. This, it is argued, helps barrels foul less and shoot more accurately. Others say minimal break-in, with patching and brushing after 10-15 rounds, is all you need. Still others contend that break-in procedures are a total waste of time and ammo — you should just load and shoot, and clean as you would normally.
We doubt if there will ever be real agreement among shooters concerning barrel break-in procedures. And one must remember that the appropriate break-in procedure might be quite different for a factory barrel vs. a custom hand-lapped barrel. This Editor has found that his very best custom barrels shot great right from the start, with no special break-in, other than wet patches at 5, 10, and 15 rounds. That said, I’ve seen some factory barrels that seemed to benefit from more elaborate break-in rituals.
What’s the best barrel break-in procedure? Eric Mayer of Varminter.com decided to ask the experts. Eric interviewed representatives of three leading barrel manufacturers: Krieger, Lothar-Walther, and Shilen. He recorded their responses on this video. In order of appearance, the three experts are:
Shilen, Krieger, and Walther Experts Talk about Barrel Break-in
Do I Need to Break-In a New Rifle Barrel?
Eric Mayer of Varminter.com says: “That is a simple question, [but it] does not necessarily have a simple answer. Instead of me repeating my own beliefs, and practices, on breaking-in a new rifle barrel, I decided to answer this one a bit differently. While we were at the 2016 SHOT Show, we tracked down three of the biggest, and most popular, custom barrel makers in the world, and asked them what they recommend to anyone buying their barrels, and why they recommend those procedures. We asked the question, and let the camera run!” Launch the video above to hear the answers — some of which may surprise you.
Barrel Break-in — Initial Inspection and Cleaning
This video explains that you should always inspect and clean the bore of your barrel before sending rounds through it. There may be remnants of the production process, such as lapping residues, that you’ll want to get out of the bore. We’ve even seen a few tiny metal pieces in some factory barrels. And it’s always wise to borescope a new barrel to see if there are visible defects in the rifling such as lands that have flawed edges — we’ve seen that on some cheaper barrels.
Barrel Break-In — Ian Klemm’s Surprising Observations
Here’s a 10-minute Vortex Nation interview with Ian Klemm. Ian, a 4-Time F-TR National Champion is one of America’s best long-range shooters. In this video, Ian explains his approach to barrel break-in, which may surprise you. Does barrel break-in even matter? Conventional wisdom says “Yes” and perhaps there’s some truth to that, but Ian argues that break-in is NOT nearly as important as the internet wants you to believe. Ian believes that you don’t need to waste a ton of time/ammo to get your barrel ready to shoot extremely accurately. This may be particularly true with premium hand-lapped custom barrels.
Barrel Break-In Procedures with Keith Glasscock
Keith Glasscock is also one of America’s greatest F-Class shooters who has finished second at the Nationals multiple times. Keith is also a highly-respected wind coach who has a popular YouTube video channel, Winning in the Wind. In this video, Keith explains his procedure for breaking-in his match barrels. He starts by bore-scoping the barrel and cleaning it. If he finds some burrs he may use some JB Bore Paste, a patch, and a worn brush and “give that throat a little scrub” (See 1:30 time-mark). He used different stroke lengths to avoid putting a “step” in the throat. When he’s satisfied he goes to the range. He fires the first five rounds, then cleans. He then fires quite a few rounds before cleaning the barrel again and beginning load development (See 8:25 time-mark).
General Barrel Break-in Procedures Recommended by Brownells
Brownells Gun Techs Steve Ostrem and Caleb Savant tackle a thorny topic: breaking in a new barrel. What IS breaking-in a barrel? And WHY do it? The rifling of a freshly machined barrel has microscopic burrs and sharp edges. “Breaking-in” is the process of putting bullets down the bore to smooth out those rough spots. The goal is to round down the sharp edges so they’re not stripping copper off a bullet as it travels the bore, which leads to fouling that leads to reduced accuracy and inconsistent groups. In a very minor way, you’re actually lapping the barrel. The breaking-in process works best on cut-rifled and button-rifled barrels. Cold hammer-forged, chrome-lined, or nitrided barrels — such as commonly found on AR-15s — may not benefit much from the process. Pistol barrels really don’t need to be broken in because larger-diameter bullets are not so much affected by tiny variations in the bore. Likewise, break-in is more helpful for a .17, .20, or .22 caliber rifle than a .45 caliber rifle.
George Gardner of G.A. Precision Talks About Barrel Break-In
G.A. Precision’s George Gardner is a leading figure in the PRS/NRL world. In this video, George makes the valid point that not all barrels require the same amount of break-in. George says some barrels require very little break-in, while others benefit from a more elaborate break-in process that helps reduce future copper and powder fouling. He calls this “seasoning” the barrel so it fouls less. For a typical barrel, George’s recommended process (4:25 time-mark) starts with one shot, then clean for three one-round cycles. This is followed by three shots then clean, with repeat 3-shot cycles if need. For cleaning George prefers nylon brushes (5:50 time-mark). NOTE: George also makes a very important point — you MUST swab the chamber and get it dry between cleaning cycles (5:30 time-mark).
For the very first day of 2023 we present a precision rifle built with a relatively new cartridge — the 6GT. Developed by George Gardner of G.A. Precision and Tom Jacobs of Vapor Trail Bullets, the 6GT was designed to have the efficiency of a 6mm Dasher without the need for case forming. It was also designed with a longer case body so it feeds better from magazines. Even with the added capacity, the 6GT is still very efficient, and can achieve good velocities with less powder than a 6mm Creedmoor.
Today’s Sunday Gunday feature rifle was smithed and tested by Gavin Gear of UltimateReloader.com. Gavin did all the gunsmithing — chambering the barrel, fitting the muzzle brake, and even laser engraving the barrel. In building this 6GT rifle, Gavin used top-tier components: BAT TR action, Krieger 28″ 1:7.5″-twist 4-groove 6mm barrel, TriggerTech Diamond Rem 700-compatible trigger, and Area 419 Hellfire Muzzle Brake. The barreled action was then fitted in a handsome and rugged MDT ACC Chassis. On top is a Zero Tech 4.5-27×50mm FFP Trace Advanced scope in 30mm Hawkins Precision high rings.
We recommend you watch the video above — it covers the rifle build, load development, and then features some remarkable shooting sequences across snowy hills in the Pacific Northwest. Gavin’s team actually used a drone to capture overhead footage of the location.
After developing a promising load with Berger 109gr LRHT bullets, Varget powder, and Alpha brass, Gavin literally headed for the hills to test his new rifle at longer ranges, shooting from bipod. His load had shot well under half-MOA at 100 yards in testing so he was hoping he could hit multiple steel targets positioned at 340 yards, 760 yards, and 1000 yards. Indeed he did, proving the rifle’s great accuracy and Gavin’s fine trigger-pulling skills. You can see the hits at these time points in the above video:
340 Yards — 18:15 time | 760 Yards — 19:00 time | 1000 Yards — 19:54 Time
Gavin’s 6GT Hit Highlights on Steel out to 1000 Yards
Building Gavin’s 6GT Precision Rifle
Gavin Gear did all the gunsmithing on this project, using his own Precision Matthews TL-1660 lathe for the chambering with an Alpha carbide 6GT reamer. The barrel work took about four hours total. Shown below is the reamer cutting the chamber, which was finished with a 0.170″ freebore and 0.270″ neck diameter. For other brands of brass you might want the chamber to have a larger 0.272″ neck diameter.
Chambering the Krieger barrel with Alpha carbide 6GT reamer, 0.170” freebore, .270″ neck diameter.
This project when smoothly, with Gavin able to install the barreled action in the MDT Chassis and fit the buttstock in an hour or so. So total build time was about five hours. One nice “finishing touch” on the project was laser engraving the 28″ Krieger barrel — a process you can see in the video below.
Laser engraving of Krieger 28″ barrel.
About the 6GT — Sort of a 6 Dasher on Steroids
6GT Cartridge Design Features
The 6GT was designed to have an optimal length and capacity for mag-fed PRS/NRL tactical rifles. The 6GT is longer than a 6mmBR and 6 Dasher, but shorter than a 6mm Creedmoor and 6.5×47 Lapua. That gives the 6GT ample case body length to feed reliably from a magazine, while the case capacity is sufficient to run popular powders at reasonable pressures. It has a 35-degree shoulder angle.
On paper the 6GT seemed like the perfect cartridge for PRS- and NRL-style centerfire competition. It has the low recoil of a 6 Dasher, with good feeding and mag compatibility. With the 6GT, a competitor can push 6mm 105gr bullets at 3000+ FPS or run heavier bullets at ~2950 FPS. With this 28″ Krieger barrel, Gavin actually achieved 3004 FPS running 109gr Bergers.
Gavin started with quality Alpha Munitions brass. The cases were then annealed with an AMP Annealer and trimmed to length with a Henderson powered trimmer (see video below). After sizing with a Forster Co-Ax press, Federal SR Primers were seated using a Primal Rights competition seater. Next the powder was measured with an A&D FX120i force restoration scale. Finally, the Berger 109gr LR Hybrid Target bullets were seated with a Forster Micrometer die, again using the smooth Forster Co-Ax press.
Initial Load Testing with Berger and Hornady Projectiles
Before it got cold and snowy, Gavin did load development, shooting from a bench with a Sinclair front rest. The Krieger cut-rifled barrel was accurate right from the start and Hodgdon Varget powder proved to be a very good choice for the 6GT.
Gavin’s 6GT boasts a MDT ACC short action chassis with SRS-X Elite buttstock, vertical grip, and MDT CKYE-POD Bipod.
Gavin did initial load testing with both Hornady 110gr A-Tip Match and Berger 109gr Long Range Hybrid Target bullets. The Berger 109gr LRHT bullets were the most promising. A variety of charge weights were tested, with Gavin settling on 34.6 grains of Varget. This delivered fine accuracy with a 3004 FPS muzzle velocity. Group size measurements with this load are shown in the chart. At 100 yards, four three-shot groups averaged 0.361 MOA, and the rifle produced a nice 0.387 MOA (0.405″) five-shot group.
———————————————— Winter Wonderland for Shooters ———————————————–
Coming Soon — Ultimate Reloader Rifles Business
Gavin Gear is in the process of opening his own gunsmithing business. He will be offering a variety of custom-built rifles for multiple disciplines — hunting, PRS/NRL, ELR, and other competitive disciplines. Gavin explains: “Ultimate Reloader is gearing up to do custom rifle work for the general public starting (hopefully) in Spring 2022. We will most likely start with complete custom rifle builds using parts from our inventory. We will focus on high-end, bolt-action rifle builds and gunsmithing, primarily Remington 700 and clones. We will entertain limited gunsmithing work outside of complete builds (i.e. chambering, muzzle threading).
The 10th Annual GA Precision/Elite Tactical GAP Grind PRO-AM was held September 30 through October 2, 2022 at the K&M Shooting Complex in Tennessee. The GAP Grind, the largest, most popular PRS match in the world, drew hundreds of amateur and pro shooters from across the USA and from many other nations. Recognized as the premier PRO-AM precision rifle match with individual and team competition, the GAP Grind has introduced thousands of new shooters to the sport since its inception. It was great to see the GAP Grind successfully mark its 10th Anniversary.
In overall standings, Daniel Hereid (photo below) finished first among Pro shooters, while Toby Phillips was top Amateur Overall. The Top Five Pros and Amateurs, along with Top Five Teams are listed overall below. There were four hardware-based divisions: Gas Gun, Open, Production, and Tactical. Pro shooter Robert Brantley led the Tactical Division and pro Ryan Kerr topped the Production Division. Notably, both Brantley and Kerr were running Bushnell Elite Tactical XRS3 riflescopes.
1st – Daniel Hereid
2nd – Francis Colon
3rd – Chad Heckler
4th – Chris Simmons
5th – Nathan Cushman
Top 5 Amateurs:
1st – Toby Phillips
2nd – Tyler Yauch
3rd – Jeff Johnson
4th – Ryder Smith
5th – Caleb Purinton
Top 5 Pro/Am Teams:
1st – Tate Streater + Toby Phillips
2nd – Chad Heckler + Jacob Strutt
3rd – Joey McConnell + Ryder Smith
4th – Daniel Herald + Vince Yarling
5th – Troy Livesay + Rick Lovely
Excellent Attendance at 10th Annual GAP Grind Event
The year’s largest PRS match drew hundreds of attendees, and more than 80,000 rounds were fired throughout the three-day event. In addition to competition stages, the GAP Grind featured a vendor area, live music and entertainment. Bushnell gave out $5,000 to the top place finishers and added over $5,000 worth of product to the prize table.
The PRS website explains how the GAP Grind is conducted and scored: “Competitors will compete as individuals and as a team; scores will be maintained for both. Trophies will be awarded to the top 5 teams, top 5 professionals, and to the top 5 amateurs. Each team member will shoot a similar course of fire with slight modifications for the Amateurs. Professionals will shoot first and unassisted. The Amateur will shoot each stage with the Professional’s assistance. Scores for both days will count toward team standings and individual standings. This allows Precision Rifle Series shooters the ability to earn 2 day PRO Series points for this match. Amateurs … may earn PRS Regional Series points.”
In this video Eagle Eye Shooting Shares Highlights from the 2022 GAP Grind
Lots of Action, with 20+ Stages
The GAP Grind is a challenging, “high tempo” match with minimal down-time between stages. Over the course of 20+ stages, competitors will fire 200+ shots at a variety of steel, paper, moving, and reactive targets out to 1,200 yards. Targets vary in size/difficulty based on the shooter’s position, distance, and time allotted. Most stages include “stressors” — i.e. time limits or required movement(s).
This extensive, 45-minute video shows many of the 2022 GAP Grind Stages
“Sponsoring the GAP Grind is always a privilege, and this 10-year mark made it especially fun,” said Matt Rice, Bushnell senior media relations manager. “GAP Grind is all about giving both experienced and new shooters a welcoming place to test and hone their skills, and our partners at K&M, G.A. Precision and PRS have done a fantastic job of making that goal a reality.”
This Armalite AR-50A1 .50 BMG rifle was modified by G.A. Precision.
If you’re a fan of big boomers, and love shooting steel, then definitely watch this Wide Open Magazine video. This covers a .50 BMG build by our friends at G.A. Precision (GAP). The rifle started as an Armalite AR-50A1 ($3359.00 MSRP). Then GAP fluted the barrel and swapped the factory muzzle brake with a more compact brake from American Precision Arms*. Then, as modified, the entire rig was given a rugged Cerakote finish.
The video has nice background music, great aerial drone footage, and of course some serious firepower. Using Hornady .50 BMG ammo, GA Precision’s George Gardner and his Wide Open friends shoot the big Fifty from the bench as well as prone. Enjoy!
About the .50 BMG Cartridge
The .50 Browning Machine Gun (.50 BMG, aka 12.7×99mm NATO or 50 Browning) is a cartridge developed for the Browning .50 caliber machine gun in the late 1910s, entering official service in 1921. Under STANAG 4383, it is a standard cartridge for NATO forces as well as many non-NATO countries.
John Browning had the idea for this round during World War I in response to a need for an anti-aircraft weapon, based on a scaled-up .30-06 Springfield design, used in a machine gun based on a scaled-up M1919/M1917 design that Browning had initially developed around 1900. According to the American Rifleman: “The Browning .50 originated in the Great War. American interest in an armor-piercing cartridge was influenced by the marginal French 11 mm design, prompting U.S. Army Ordnance officers to consult Browning. They wanted a heavy projectile at 2700 FPS, but the ammunition did not exist. Browning pondered the situation and, according to his son John, replied, ‘Well, the cartridge sounds pretty good to start. You make up some cartridges and we’ll do some shooting’.”
* In the video, George mistakenly says “American Patriot Arms”, but the brake is made by Georgia-based American Precision Arms.
Are you looking to get started in PRS and tactical/practical competitions? Here are three videos that can help you improve your game. These videos feature two top PRS competitors, and George Gardner of G.A. Precision, considered one of the founding fathers of the PRS game. You’ll find other PRS-focused videos on the Long Range Precision Shooters YouTube channel.
PRS Ace Shows Skills Barricade Technique — with POV Video
This first video features 2015 PRS Champion David Preston shooting the PRS Skills barricade. Dave Preston is widely considered the best in the nation running this PRS stage. Dave nearly always shoots 100% with the fastest recorded time. In this video you’ll see him successfully engage all eight shots in under 43 seconds — that’s crazy fast. This includes a POV sequence (4:35 time-mark) showing the actual view through Dave’s scope.
The PRS Skills Barricade is an 8-round, 4-position stage featured at most PRS matches. It’s called a “Skills Stage” as it is run the same way at every national match and gives shooters the ability to compare skill levels based on hit percentage and speed. The target is a 10″ plate at 400 yards. There are four different positions, with two shots each. Most people run this stage in about 70 seconds, some in the mid-60s, while Dave does it in the low 40s!
Know Your Limits PRS Stages — Pro Tips
The Second video showcases how 2018 Oklahoma PPS Champion Clay Blackketter approaches Know Your Limit Stages. With these particular type of stages you have to make judgment calls about your rifle’s accuracy and your ability to hold on target. You can boost your score by shooting the smallest target(s), but you risk losing points if you miss. Clay explains how best to manage a Know Your Limits stage.
Cartridge Choice for PRS and Tactical Competition
Today’s third video reviews many of the different caliber selections popular for PRS-style competition. The video examines pros and cons of various cartridge choices, focusing on accuracy, recoil, mag-feeding, and value for money. This segment features G.A. Precision owner/founder George Gardner.
Most Top PRS shooters are using 6mm catridges these days. These deliver excellent accuracy with lower recoil and cheaper bullet cost. Popular choices include 6 Dasher, 6mm Creedmoor, 6XC, 6-6.5×4 and the new 6GT cartridge, which is sort of a stretched version of a 6mmBR. It has a bit more case length for better feeding, and greater case capacity than a 6BR so you can shoot 105-108 grain bullets at the 2950 fps node.
CLICK HERE for a full write-up on a 6GT rifle build by Mike McCasland (Texas Precision). This includes load development suggestions and a 6GT reamer print. The most common 0.120″ freebore chamber allows for the majority of high-BC 6mm projectiles found in both F-Class and PRS. Mike had good luck with the pointed 107gr Sierra Match Kings (SMK), as well as the 110gr Hornady A-Tips in his rifle, shown below:
Practical Shooter’s Guide
Thinking of getting started in the Practical/Tactical shooting game? Looking for ways to be more stable when shooting from unconventional positions? Then you may want to read Marcus Blanchard’s Practical Shooter’s Guide (A How-To Approach for Unconventional Firing Positions and Training). Unlike almost every “how to shoot” book on the market, Blanchard’s work focuses on the shooting skills and positions you need to succeed in PRS matches and similar tactical competitions. Blanchard provides clear advice on shooting from barricades, from roof-tops, from steep angles. Blanchard says you need to train for these types of challenges: “I believe the largest factor in the improvement of the average shooter isn’t necessarily the gear; it’s the way the shooter approaches obstacles and how they properly train for them.”
The 6mm GT (aka 6GT) cartridge was conceived as a “bigger Dasher” for PRS and NRL competition. The 6mm GT’s creators wanted 6mm Dasher accuracy and moderate recoil delivered via a cartridge with a slightly longer case body for better mag-feeding, longer neck for seating flexibility, and more moderate pressures. So far the 6GT has performed very well in PRS competition. Today’s story is a bit different — this is about an experiment — running a 6mm GT in an F-TR type rifle. Understand that, under current NRA rules, you may only shoot .223 Rem (5.56×45) or .308 Win (7.62×51), in official, sanctioned F-TR competition, but the 6GT is fine for F-Open. Mike McCasland wanted to see the potential of the cartridge for long-range target shooting, so he put a 6mm GT-chambered Bartlein barrel on a nice custom rifle with McMillan XIT stock and Kelbly F-Class Panda action. The results were impressive.
6mm GT — New Cartridge with Multi-Discipline Potential
Story by Mike McCasland, Texas Precision
The 6mm GT began garnering attention within PRS circles in early 2019. It promised to shoot 105-110gr 6mm bullets at 2950-3000 FPS, yet not suffer from mag-feed issues sometimes found with 6mmBR variants such as the 6 Dasher, 6BRX, and 6BRA. Moreover, since it burned less powder, the 6mm GT promised increased barrel life compared to the 6mm Creedmoor or 6XC. The 6mm GT case size should still work with the accurate powders in the Varget burn-range. I found the 6GT also worked great with H4350.
As someone who aspired to building a repeater and jumping into the PRS game, and had a spare F-TR rifle sitting around, I thought it would be fun to build up a 6mm GT to see if there was any merit to the hype. My smith, Wes Ripley of RIP Precision in Texas, builds a lot of PRS rigs, and already had the reamer on hand (a 0.120″ freebore variant).
Whidden Gunworks had some 6mm GT FL bushing die kits in stock, so I figured why not see what all the fuss was about? At the very least I could play around with the 6mm GT in F-Open Class at local club matches to see how it compared to the 6BRA, 6 Dasher, and other popular 6mm cartridges.
How the Project Got Started with Backup F-TR Rig
My 6mm GT build really started as a project spawned purely from COVID-19 Isolation boredom. This rifle primarily serves as a backup F-TR gun, and it had been relegated to performing some load development on .308 barrels, so I could spin new ones on my main match rifle. The only problem was, I had run out of .308 barrels that needed load development. So, I basically had an ideal test platform just collecting dust in the safe. All I needed was a 6mm GT-chambered barrel, since (like the 6mmBR) the 6mm GT works in a short action with a .308 Win-sized bolt-face.
6mm GT Rifle Specifications:
Action: Kelbly Panda F-Class SA RB/RP
Stock: McMillan XIT with RAD 2A
Barrel: 30″ 5R Bartlein 1:7.5″-Twist, HV Contour
Scope: Vortex Golden Eagle 15-60x52mm
Trigger: Jewell Benchrest, about 2 ounces
Bipod: Phoenix Precision
About the 6mm GT Cartridge
BRASS — The first thing you’ll find is cartridge brass choices for the 6mmGT are rather limited currently. At present, the only commercial options are Hornady and Alpha Munitions. For the die-hard Lapua fans, you can technically make 6mm GT brass from 6.5×47 Lapua, however that process is very labor-intensive.
I have used both Hornady and Alpha brass in this rifle and haven’t noticed much difference between the two. I will say that my batch of Alpha brass was slightly softer than Alpha brass I’ve used in other calibers; you could feel a difference when neck turning cases. I’m unsure if that’s a batch issue, or something specific to their 6mm GT brass as a whole. As far as performance, there was little discernable difference. Oddly enough, the Hornady brass seemed to have slightly less case capacity than the Alpha; with most other cartridges it’s the other way around.
POWDERS — The 6mm GT was designed with Hodgdon Varget in mind, and that popular powder works exceedingly well in this platform. That said, the 6mm GT can work with a wide variety of powders, some yielding better performance than Varget.
I’ve tried a multitude of powders during my initial 6mm GT load development: Varget, Shooters World Precision, RL16, VV N140, H4350, and RL-15 to name a few. In my barrel, Hodgdon H4350 seems to deliver the best velocity/accuracy combination. SD and ES also seemed to be the lowest with H4350.
Load Development for the 6mm GT — Many Powders Tested
BULLETS — The most common 0.120″ freebore chamber allows for the majority of high-BC 6mm projectiles found in both F-Class and PRS. I had good luck with the pointed 107gr Sierra Match Kings (SMK), as well as the 110gr Hornady A-Tips in my rifle. For those looking to run the heavier 112-115 grain 6mm offerings, I believe GAP designed a 0.160″ freebore reamer that gets those bullets out of the neck/shoulder junction. Shown below is the 0.120″ freebore JGS reamer print:
SUMMARY — Good Cartridge with Much Potential
Generally speaking, I think the 6mm GT is a good little round. Some may not subscribe to this theory, but I believe some cartridges are inherently easier to tune than others. I’m not sure the 6mm GT is as easy-to-tune as a 6mmBR, 6 Dasher, or 6 BRA, but I don’t think it lags that far behind.
With relatively little trouble, I was able to find loads with both Varget and H4350 that would consistently shoot very well — 0.2 to 0.3 MOA. Moreover, I found the 6GT cartridge lives up to the velocity claims made by G.A. Precision. I was easily able to push the 110gr A-Tips to 2950 FPS, and the 107gr SMKs to low 3000 FPS range without any pressure signs, or unnecessary wear and tear on the brass.
As a fun test, I ran my 6mm GT rifle in a local 1000-yard F-Class match with the 110gr A-Tips, just to see just how well they would perform. Although wind conditions of the day and some E-Target issues prevented my 6mm GT rig from getting the better of the larger 7mm and .30-Cal rifles, the 6mm GT proved itself an accurate little round at distance. Here is a 1000-yard ShotMarker target:
After putting several hundred rounds through my 6mm GT rifle, I anticipate building another 6GT on a repeater action to give PRS a try. I think if you are looking for a dual-purpose rifle that can run tactical matches (with 100% feeding reliability), and can also be used for mid-range, F-Open Class competition, the 6mm GT would be a very good option.
About the author, Mike McCasland:
Mike McCasland is an avid shooter who competes regularly in F-Class matches. Based in Texas, Mike is the creator of the Texas Precision YouTube Channel. There you’ll find many videos covering reloading, gun projects, and marksmanship. Mike has done some notable product reviews including a comparison test of Micrometer Competition Seating Dies. To access Mike’s YouTube Channel, CLICK HERE.
Can’t get enough gun content on your home computer? Now you can stream informative audio broadcasts to your mobile device. In addition to its popular weekly TV shows, Shooting USA now offers podcasts on gun topics. These podcasts feature interviews with ace shooters, notable gunsmiths, and leading firearms industry executives. There are now 141 Shooting USA Podcast episodes available for streaming. Or you can download a podcast to your mobile device for later listening. All Shooting USA Podcast content is free. Use these links to access all Shooting USA Podcasts (123 audio shows):
Now you can listen to timely and entertaining Shooting USA Podcasts, hosted by Jim and John Scoutten. They are available on both Podbean and iTunes.
Here are five of our favorite Shooting USA Podcasts. These include interviews with G.A. Precision owner George Gardner, legendary shooter Jerry Miculek, and ace pistolero Max Michel, who may be the fastest handgunner on the planet. Click each graphic to launch the PodBean player page for that Podcast.
Watch Max Michel Speed Drill (This Guy is Blazing Fast!)
As someone who aspired to building a repeater and jumping into the PRS game, and had a spare F-TR rifle sitting around, I thought it would be fun to build up a 6mm GT to see if there was any merit to the hype. My smith, Wes Ripley of RIP Precision in Texas, builds a lot of PRS rigs, and already had the reamer on hand (a 0.120″ freebore variant).
BRASS — Editor’s Report: Lapua now offers excellent 6mm GT (aka 6GT) Lapua brass, product #4 PH6060C. You can also get very good Alpha Munitions 6mm GT brass and Peterson 6mm GT brass. Hornady produces 6mm GT brass as well, but we recommend Lapua, Alpha, or Peterson over Hornady. Lapua 6mm GT brass is in-stock now at Midsouth for $136.99/100 or Mile-High Shooting for $130.00/100. Alpha 6mm GT brass is available from K&M Precision for $130.00/100, and 500-ct bulk packs of Peterson 6mm GT Brass are available at Grafs.com for $548.14.
SUMMARY — Good Cartridge with Much Potential
We doubt if there will ever be real agreement among shooters concerning barrel break-in procedures. And one must remember that the appropriate break-in procedure might be quite different for a factory barrel vs. a custom hand-lapped barrel. This Editor has found that his very best custom barrels shot great right from the start, with no special break-in, other than wet patches at 5, 10, and 15 rounds. That said, I’ve seen some factory barrels that seemed to benefit from more elaborate break-in rituals.
George Gardner was kind enough to send us 50 pieces of Pre-Production Alpha 6GT brass for preliminary testing. Like the cases I formed from 6.5×47 Lapua brass, the Alpha 6GT brass will use a small rifle primer. Purchased direct from 
