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August 27th, 2023

Sunday GunDay: 6GT Cartridge for PRS/NRL Competition

6GT Cartridge Alpha Munitions GA Precision PRS NRL brass 6.5x47 Lapua fire-formed neck-turn project

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.

load development 6GT 6mm GT report cartridges

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 Cartridge Alpha Munitions GA Precision PRS NRL brass 6.5x47 Lapua fire-formed neck-turn project
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.

6GT Cartridge PRS NRL brass 6.5x47 Lapua 6GT 6mm Dasher cartridge fire-formed neck-turn project

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

6GT Cartridge Alpha Munitions GA Precision LabRadar PRS NRL brass 6.5x47 Lapua fire-formed neck-turn project

Alpha Munitions Pre-Production 6GT Brass
6gt brass cartridge Alpha Munitions PRS 6mm DasherGeorge 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!

6GT Cartridge 600 yard target PRS NRL brass 6.5x47 Lapua fire-formed neck-turn project

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.

6GT Cartridge 600 yard target PRS NRL brass 6.5x47 Lapua fire-formed neck-turn project

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

mike mccasland 6mmGT 6 GT alpha brass 6BRA PRS F-ClassBRASS — 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.

mike mccasland 6mmGT 6 GT alpha brass 6BRA PRS F-Class

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
mike mccasland 6mmGT 6 GT alpha brass 6BRA PRS F-Class

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:

mike mccasland 6mmGT 6 GT alpha brass 6BRA PRS F-Class

mike mccasland 6mmGT 6 GT alpha brass 6BRA PRS F-ClassSUMMARY — 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:

mike mccasland 6mmGT 6 GT alpha brass 6BRA PRS F-Class

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.

Permalink - Articles, Bullets, Brass, Ammo, Gear Review, Reloading, Tactical No Comments »
August 27th, 2023

Those Were the Days — Hodgdon Powder Prices 45 Years Ago

historic hodgdon powder prices inflation chart table O.K. Weber

Have inflation (and supply chain shortages) affected the price of powder? You bet. Probably WAY more than you could imagine. Forum member “Two Time HM LR” posted this interesting photo (above) showing Hodgdon powder prices from 1978, as sold by O.K. Weber in Oregon.

Eight Pounders under $45.00 in 1978
Now the prices — $20 to $44 — may not get your attention at first. But take note that these numbers are for EIGHT pound containers. Yep eight-pounders were all under $45! For example, H4895 was $44 for 8 pounds back in 1978, 45 years ago. And H335 was $20 for eight pounds — that’s just $2.50 per pound!

These days a single pound of a desirable powder such as H4831 might cost $60+ at some stores IF you can find it at all. On Hodgdon’s web site, H4831 powder is priced at $54.99 per pound in August 2023. Using that current $54.99/lb figure, H4831 is now TEN times higher than it was in 1978, when H4831 cost $44 for 8 pounds, i.e. $5.50 per pound.

Here are some comments from our Forum Members:

“Heck those prices are just about the same as current ones, just a little smaller container now.” — Joe

“I’ve got some H4831 in a can marked ‘WWII Surplus Powder’ with a price tag of $2.75. We’ll never see that again either.” Rick in Oregon

“1978 prices and 2022 income would be nice. Unfortunately that doesn’t work. If you compare prices and income, powder cost about the same. You also have to discount the temporary gouging that we are seeing.” — Tmwinds

“So I used to buy gas for 10 cents per gallon and they’d pump it, check the oil, and clean the windshield.” — Pirate Ammo

One comment suggests that the powder price hike actually tracks general U.S. currency inflation over the last four decades. So perhaps powder price increases are not as bad as they seem, when compared to how all prices have risen since 1978:

“Using H4895 as a comparison basis at $58.50 (list price) in 1978 calculates it to $275 in todays money. Looking at Powder Valley prices it looks like around [$340 in August 2023] for the same item in todays money [a 24% increase in real dollars]. Availability is another issue though and if someone is really needing powder they may well have to pay above suggested retail.” — Drover

Permalink Bullets, Brass, Ammo, Reloading 1 Comment »
August 27th, 2023

Position Shooting — Tips from Gary Anderson and Jamie Gray

rimfire sporter position shooting Gary Anderson jamie gray air rifle cmp

Want to learn the basics of position shooting? Then you should check out an article by Gary Anderson, DCM Emeritus, in On the Mark digital magazine (Summer 2014, pp. 6-13). This article covers all the key elements: body position (prone, sitting, standing), sling use/adjustment, sight picture, aiming process, and trigger control. While this 8-page article was specifically written for Rimfire Sporter shooters, the techniques described by Anderson apply to all types of position shooting, whether you shoot air rifles, smallbore rifles, or centerfire rifles.

CLICK HERE for Position Shooting Article in On The Mark Magazine
NOTE: This is a large PDF Document — it may take some time to fully load. Scroll to page 6-13.

rimfire sporter position shooting Gary Anderson

Here’s what Anderson says about aiming — how to keep your sights steady and get them centered on the middle of the target:

Trigger Contact and Center
rimfire sporter position shooting Gary AndersonAs soon as aiming at the target begins, the index finger must move from the trigger-guard to contact the trigger. It is important to get initial pressure on the trigger as soon as aiming begins. Then the shooter must focus on the sight picture and centering the sight picture movements over the aiming point. No one, not even champion shooters, can hold the aligned sights perfectly still. The sights are going to move a little bit or a lot, depending on the shooter’s skill level. The secret is to center those sight picture movements over the aiming point on the target (see trace illustration) before pulling the trigger.

When the sight picture movements on the target are centered, the last step in firing the shot is to add… smooth pressure on the trigger until the shot breaks.

Anderson also discusses the 5 Basics of Shot Technique:

rimfire sporter position shooting Gary Anderson

BONUS: Olympic Gold Medalist Jamie Gray

standing position shooting jamie gray gold medal

Here’s an interesting video about three-position shooting. Produced by GOnra Media, this video demonstrates rifle hold and body alignment for prone, standing, sitting, and kneeling positions. Olympic Gold Medalist Jamie Gray demonstrates the proper stance and position of arms and legs for each of the positions. Ideally, in all of the shooting positions, the shooter takes advantage of skeletal support. The shooter should align the bones of his/her arms and legs to provide a solid foundation. A shooter’s legs and arms form vertical planes helping the body remain stable in the shooting position.

Olympic Gold Medalist Jamie Gray Demonstrates Shooting Positions

In the above video, Jamie is using an air rifle, but the stance and holds she demonstrates also work for rimfire and centerfire rifle shooting.

standing position shooting jamie gray gold medal

Permalink Competition, Shooting Skills No Comments »