In our Shooters’ Forum, you’ll find a lengthy thread about accuracy problems with a Savage LRPV, chambered in 6mmBR. The gun would repeatedly split groups at 100 yards, and at 300 yards, the “flyers” would open up the groups to 1.5 MOA or larger. Interestingly, the factory test target (at right) showed a split group — not a good sign.
The gun’s owner, forum member LR_Shooter, tried a variety of tweaks: “I did this, done that… [changed] torque, tang floated, bedded action, recut chamber, and [adjusted firing pin]”. But nothing really helped. Frustrated, LR_Shooter asked his fellow Forum members for help. Much advice was proffered, including the novel idea of removing the middle action screw in the Savage 3-screw target action. Some of the advice proved helpful, but none of the suggested remedies produced a major improvement. This rifle, out of the box, tossed flyers and no amount of tweaking (or changes in shooting technique) really cured the basic problem. That is, until, the factory barrel got replaced…
New Criterion Pre-Fit Barrel Works Wonders
LR_Shooter acquired a Criterion pre-fit barrel from Jim Briggs at Northland Shooters Supply (NSS). These pre-fits are designed for easy installation with the standard Savage barrel nut. Wouldn’t you know it, with a new 30″ heavy-contour barrel on the LRPV, the gun started shooting way better. No more crazy fliers, no more split groups, no more excessive vertical. And the improvement came without any other major modifications. LR_Shooter reports: “I got a replacement barrel from Jim at NSS. It is a 30″ bull Criterion barrel. So far, without playing with torque screws and having my old setup… I’m very satisfied with the barrel I got. Now I have no problem getting [groups] under 0.25 MOA. Finally this thing can shoot!” The targets below, shot with the new Criterion barrel, speak for themselves. The left target was shot at 100 yards, while the target on the right was shot at 300 yards (very impressive).
Targets Shot with Savage LRPV Fitted with Criterion Barrel
Moral of the Story — Sometimes A New Barrel Really Is the Right Solution
All of us have struggled at times with a rifle that won’t live up to expectations. This Editor personally struggled for over a year with a .260 Rem Savage with a factory tube. The gun tended to split groups and the POI walked as the barrel heated. I tried one powder/primer combination after another, working through a variety of seating depths over many months. I was persistent. Out of stubbornness, I just believed that sooner or later I’d find the magic load.
Well folks, sometimes there’s really nothing you can do about a sub-par barrel. It is what it is. To really improve a gun’s accuracy (particularly a gun with a factory tube), you may need to open your wallet and get a quality aftermarket barrel. Spending months trying one recipe after another may simply be an overwhelming waste of powder, bullets, and your precious time.
Albert Einstein supposedly said: “Insanity is defined as doing the same thing over and over again, and expecting different results.” Well that sort of describes my efforts with my .260 Rem. Once I had enough evidence that my barrel split groups no matter what load combo (and seating depth) I tried, it was time to pony up for a new barrel. When I did finally screw on a nice PacNor 3-groove Supermatch, that Savage suddenly became a true tack-driver. As re-chambered in 6mmBR with the Pac-Nor, in calm conditions, my Savage will now consistently shoot in the twos with heavy bullets, and it can sometimes dip down into the ones with Berger 80gr flat-base bullets. The moral of the story here is simple — don’t waste weeks or months chasing your tail with a barrel that just won’t deliver (after a reasonable amount of testing). Save up for a custom barrel, get it chambered properly, and stop your cycle of frustration.
Contact Information for Northland Shooters Supply:
E-mail: briggs.j-b@q.com (that is Q.com not G.com)
Phone: (763) 682-4296
Fax: (763) 682-6098
Mailing address:
P.O. Box 333
Buffalo, MN 55313
Larry Scott, who runs GreatScottShooters.com, has a friend, Ray Mabry, who is a very talented wood-worker and carver. Ray does master-grade decorative work and checkering on gunstocks, and he also carves realistic nature subjects from wood. Larry says: “If you need stock checkering/carving or any wildlife creation, check out a friend of mine, Ray Mabry. His finished products are superb.”
Ray Mabry is a member of our AccurateShooter Forum, and you can see many fine examples of his work in this FORUM Thread. Ray tells us: “I do this work as a hobby. I do checkering and relief-carving on rifles. I also carve out of solid tupelo and bass blocks of wood. Along with rifle stock work, I carve wildlife subjects — I’ve carved eagles, owls, quail, ducks, and even prairie dogs. If you have a project in mind, call me at 270-885-6066 or send email to: rayzr [at] twc.com.”
Barrel-maker Dan Lilja’s website has an excellent FAQ page that contains a wealth of useful information. On the Lilja FAQ Page as you’ll find informed answers to many commonly-asked questions. For example, Dan’s FAQ addresses the question of barrel life. Dan looks at factors that affect barrel longevity, and provides some predictions for barrel life, based on caliber, chambering, and intended use.
Dan cautions that “Predicting barrel life is a complicated, highly variable subject — there is not a simple answer. Signs of accurate barrel life on the wane are increased copper fouling, lengthened throat depth, and decreased accuracy.” Dan also notes that barrels can wear prematurely from heat: “Any fast varmint-type cartridge can burn out a barrel in just a few hundred rounds if those rounds are shot one after another without letting the barrel cool between groups.”
Q. What Barrel Life, in number of rounds fired, can I expect from my new barrel?
A: That is a good question, asked often by our customers. But again there is not a simple answer. In my opinion there are two distinct types of barrel life. Accurate barrel life is probably the type most of us are referencing when we ask the question. But there is also absolute barrel life too. That is the point where a barrel will no longer stabilize a bullet and accuracy is wild. The benchrest shooter and to a lesser extent other target shooters are looking at accurate barrel life only when asking this question. To a benchrest shooter firing in matches where group size is the only measure of precision, accuracy is everything. But to a score shooter firing at a target, or bull, that is larger than the potential group size of the rifle, it is less important. And to the varmint hunter shooting prairie dog-size animals, the difference between a .25 MOA rifle or one that has dropped in accuracy to .5 MOA may not be noticeable in the field.
The big enemy to barrel life is heat. A barrel looses most of its accuracy due to erosion of the throat area of the barrel. Although wear on the crown from cleaning can cause problems too. The throat erosion is accelerated by heat. Any fast varmint-type cartridge can burn out a barrel in just a few hundred rounds if those rounds are shot one after another without letting the barrel cool between groups. A cartridge burning less powder will last longer or increasing the bore size for a given powder volume helps too. For example a .243 Winchester and a .308 Winchester both are based on the same case but the .308 will last longer because it has a larger bore.
And stainless steel barrels will last longer than chrome-moly barrels. This is due to the ability of stainless steel to resist heat erosion better than the chrome-moly steel.
Barrel Life Guidelines by Caliber and Cartridge Type
As a very rough rule of thumb I would say that with cartridges of .222 Remington size you could expect an accurate barrel life of 3000-4000 rounds. And varmint-type accuracy should be quite a bit longer than this.
For medium-size cartridges, such as the .308 Winchester, 7×57 and even the 25-06, 2000-3000 rounds of accurate life is reasonable.
Hot .224 caliber-type cartridges will not do as well, and 1000-2500 rounds is to be expected.
Bigger magnum hunting-type rounds will shoot from 1500-3000 accurate rounds. But the bigger 30-378 Weatherby types won’t do as well, being closer to the 1500-round figure.
These numbers are based on the use of stainless steel barrels. For chrome-moly barrels I would reduce these by roughly 20%.
The .17 and .50 calibers are rules unto themselves and I’m pressed to predict a figure.
The best life can be expected from the 22 long rifle (.22 LR) barrels with 5000-10,000 accurate rounds to be expected. We have in our shop one our drop-in Anschutz barrels that has 200,000 rounds through it and the shooter, a competitive small-bore shooter reported that it had just quit shooting.
Remember that predicting barrel life is a complicated, highly variable subject. You are the best judge of this with your particular barrel. Signs of accurate barrel life on the wane are increased copper fouling, lengthened throat depth, and decreased accuracy.
Benchrest Barrel Life — You May Be Surprised
I thought it might be interesting to point out a few exceptional Aggregates that I’ve fired with 6PPC benchrest rifles with barrels that had thousands of rounds through them. I know benchrest shooters that would never fire barrels with over 1500 shots fired in them in registered benchrest matches.
I fired my smallest 100-yard 5-shot Aggregate ever in 1992 at a registered benchrest match in Lewiston, Idaho. It was a .1558″ aggregate fired in the Heavy Varmint class. And that barrel had about 2100 rounds through it at the time.
Another good aggregate was fired at the 1997 NBRSA Nationals in Phoenix, Arizona during the 200-yard Light Varmint event. I placed second at this yardage with a 6PPC barrel that had over 2700 rounds through it at the time. I retired this barrel after that match because it had started to copper-foul quite a bit. But accuracy was still good.
While AccurateShooter.com focuses on rifles, we know that a large percentage of our readers own handguns, with 1911-style pistols being particular favorites. For you 1911 owners, here are six short videos from Brownells showing how to customize a 1911-style pistol with after-market upgrades.
How to Accessorize Your 1911
This six-part series by Brownells provides step-by-step instruction on how to accessorize your 1911. The videos cover changing out the mainspring housing, magazine release, slide release, hammer, guide rod, and installing a group gripper.
We often receive questions from varmint hunters and AR shooters regarding barrel length. They want to know how much velocity they will loose if they run a shorter barrel in their .223-Rem rifle. Our friends at Rifleshooter.com did a test that provides some surprising answers to that question.
With barrels, one always wonders “Can a little more length provide a meaningful velocity gain?” To help answer that question, Rifleshooter.com performed an interesting test, cutting the barrel of a .223 Rem rifle from 26″ all the way down to 16.5″. The cuts were made in one-inch intervals with a rotary saw. At each cut length, velocity was measured with a Magnetospeed chronograph. To make the test even more interesting, four different types of .223 Rem/5.56 ammo were chron’d at each barrel length.
Test Barrel Lost 25.34 FPS Per Inch (.223 Rem Chambering)
How much velocity do you think was lost, on average, for each 1″ reduction in barrel length? The answer may surprise you. The average speed loss of the four types of .223/5.56 ammo, with a 9.5″ shortening of barrel length, was 240.75 fps total (from start to finish). That works out to an average loss of 25.34 fps per inch. (See inch-by-inch data HERE.)
5.56/.223 Barrel Cut-Down Speed Test 26″ to 16.5″
Start FPS at 26″
End FPS at 16.5″
Total Loss
Average Loss Per Inch
UMC .223 55gr
3182*
2968
214
22.5 FPS
Federal M193 55gr
3431
3187
244
25.7 FPS
Win m855 62gr
3280
2992
288
30.3 FPS
Blk Hills .223 68gr
2849
2632
217
22.8 FPS
*There may have been an error. The 25″ velocity was higher at 3221 fps.
Rifleshooter.com observed: “Cutting the barrel from 26″ to 16.5″ resulted in a velocity reduction of 214 ft/sec with the UMC 223 55-grain cartridge, 244 ft/sec with the Federal M-193 cartridge, 288 ft/sec with the Winchester M855 cartridge and 217 ft/sec with the Back Hills 223 68-grain match cartridge.”
How the Test Was Done
The testers described their procedure as follows: “Ballistic data was gathered using a Magnetospeed barrel-mounted ballistic chronograph. At each barrel length, the rifle was fired from a front rest with rear bags, with five rounds of each type of ammunition. Average velocity and standard deviation were logged for each round. Once data was gathered for each cartridge at a given barrel length, the rifle was cleared and the bolt was removed. The barrel was cut off using a cold saw. The test protocol was repeated for the next length. Temperature was 45.7° F.”
Much Different Results with 6mmBR and a Longer Barrel
The results from Rifleshooter.com’s .223/5.56 test are quite different than the results we recorded some years ago with a barrel chambered for the 6mmBR cartridge. When we cut our 6mmBR barrel down from 33″ to 28″ we only lost about 8 FPS per inch. Obviously this is a different cartridge type, but also our 6mmBR barrel end length was longer than Rifleshooter.com’s .223 Rem start length. Velocity loss may be more extreme with shorter barrel lengths.
If you are at the NRA Annual Meetings & Exhibits today, you might want to visit the Remington booth. 2016 marks Remington’s 200-year Anniversary, and Remington’s booth features displays showcasing the company’s rich history over the past two centuries. Layne Simpson notes: “When Eliphalet Remington II hammered out his first rifle barrel in his father’s commercial iron forge in 1816, little did he realize that 200 years later we would be celebrating such an exceptional milestone.”
NRA Publications has created a free 68-page eBook that traces the history of Remington, America’s oldest gunmaker. The book includes many well-researched historical articles, a company time-line, and the 2016 Remington Gun Guide. Get the FREE Remington 200th Anniversary Commemorative Book HERE: Remington History Book and 2016 Gun Guide.
The book contains many interesting feature stories. A fascinating article by Garry James, Remington Goes to War, covers the history of Remington firearms used by the American military. Interestingly, the first complete rifles built at the Remington factory were Model 1841 muskets contracted by the U.S. Army Ordnance Department in 1845.
In another in-depth article (featuring a fascinating, illustrated Remington timeline), NRA Museum Senior Curator Philip Schreier recounts the remarkable history of Remington firearms and ammunition. The From the Forge article by Layne Simpson highlights the key rifle models developed by Remington, from muskets to the legendary Model 700. Finally, John Zent writes about Remington’s manufacturing plants in Ilion, NY, and Huntsville, AL. Zent explains the processes (both traditional and ultra-modern) Remington uses to make all types of firearms.
Pac-Nor Production Manager Casey Dichter says the Sunnen hone produces a consistency in bore diameter that is much superior to hand-lapping. The Sunnen machine has all but eliminated the standard pre-rifling lap. “You can really tell the difference between a bore that was honed before rifling and one that was [only] lapped”, notes Dichter.
Gun Barrel Honing System Hits Target for Pac-Nor Barreling
Manufacturing precision rifle barrels has always been something of an art that involves hand lapping of the bore surface twice, before and after the rifling profile is cut or swaged in by a rifling button. In fact, a bright, hand-lapped bore is considered one of the hallmarks of a precision rifle barrel, despite the inherent variations from manual work done by people who get bored and tired from the monotonous chore. Pac-Nor Barreling, Inc. set its sights on this issue more than a year ago and hit the X-ring with the newly developed Sunnen HTE honing machine. The machine has all but eliminated Pac-Nor’s pre-rifling lap, which is the more difficult and time-consuming of the two laps. Pac-Nor is also producing as many custom barrels as ever, but with a slightly smaller staff. “Our objectives with the hone were to build a better product with less labor, and the honing machine has exceeded my expectations,” said Pac-Nor Production Manager Casey Dichter. “The hone produces a consistency in bore diameter that is head and shoulders above lapping, within two to three millionths of an inch end-to-end when it’s really dialed in,” he said. “This, in turn, improves the consistency of the rifling process by minimizing variation in the depth of the grooves. We still finish lap after rifling, but it’s easier because we just polish off the fine crosshatch finish that may be left after honing and rifling.”
The Sunnen hone secures the barrel blank in a 3-jaw chuck, with honing oil pumped into one end while the tool works from the opposite end. Sunnen’s specialized Long Bore Tool uses metal-bond diamond or CBN superabrasives to quickly remove reamer marks, waviness, tight spots and other imperfections left by upstream processes.
Honing is an ideal replacement for hand lapping barrel blanks before rifling. It quickly removes reamer scratches and surface waviness without labor-intensive hand lapping. A typical 600-grit abrasive can produce a 6-10 microinch Ra (0.15 to 0.25 µm) finish in a reamed barrel blank. By producing a consistent bore diameter (±0.0001″ or less), parallelism, roundness and surface finish end to end, honing yields more consistent performance from rifling buttons and cutters, resulting in a constant groove depth. The ideal bore geometry reduces distortion of the bullet shape.
Pac-Nor’s barrel-making process starts with cutting and facing premium bar stock, followed by gun drilling, done by four Pratt & Whitney twin-spindle machines and an Eldorado CNC twin spindle. After reaming, the barrels are gauged for size. Depending on the condition of the reamer, 0.0004″ to 0.0007″ of material is left in the bore. This must be manually lapped out or honed out to final size for rifling. “Everyone who works here has done hand-lapping,” said Dichter. “It’s an unpleasant job, particularly if the reamer is starting to get dull. Lapping may take 10 to 45 minutes, depending on the caliber of the barrel. We tried to shorten this, but when chatter marks get ‘ironed’ into the surface by the rifling button, the finish lap is even longer and more difficult, so there is no advantage. With lapping, too, there is potential for variation, simply because it’s a manual process. Lapping can also be a production limiter and in our region we have a very small labor force to draw on when we want to grow.”
Pac-Nor cuts and faces premium bar stock, then gun drills on one of five twin-spindle machines, followed by reaming of the blanks. This rack of barrel blanks awaits completion.
The company had explored honing in the nineties, but re-visited the idea when Sunnen introduced its HTE honing machine in 2014. The HTE is a horizontal machine that can hone small-bore rifle barrels, with a diameter range of 0.150″ to 0.790” (4-20 mm), and lengths up to 60″ (1,524 mm). Designed specifically for long small bores, the machine features an extremely sensitive drive and tool feed system that provide maximum protection against tool overload/breakage. Tool specific force limits and run settings are stored in the touch-screen PC control, allowing the system to sense tight sections in the bore and correct them automatically.
Sunnen also developed a new Long-Bore Tool (LBT) designed to take on industry’s most difficult honing challenges in small bores of .17 caliber rifle barrels. The tool quickly remove reamer marks, waviness, tight spots and other imperfections left by upstream processes. The LBT utilizes metal-bond diamond or CBN super-abrasives for high productivity, long life and fast cycle times. Precision-machined of through-hardened tool steel, the LBT can produce bore accuracies of 0.000027″ (0.0006 mm) for diameter, roundness, and taper – from first part to last.
“We are currently honing about 80 percent of what we make and will do more as we acquire the tools in different calibers,” said Dichter. “Although there is a trade-off in cycle time and abrasive cost for additional honing, we are still able to run our reamers two to three times longer than when we lapped alone. With a hand lap, the time and effort increase when the reamer is getting dull.”
After honing, each barrel is inspected again before rifling with a pull-button. Pac-Nor makes its own Accu-Twist carbide rifling buttons and can provide different rifling styles, including polygonal, per the customer’s choice. A button is attached to a rod and the rod is pulled through the barrel. The company’s hydraulic rifling machine utilizes a CNC-machined twist bar with a helix angle that matches the twist rate requested by the customer. The final twist rate is confirmed afterward using a Barrel-Scan electro-optical twist measurement system.
The barrel is then stress-relieved in a tempering furnace, followed by contouring of the outer shape and final, finish lapping of the bore. “During the finish lap, you can really tell the difference between a bore that was honed before rifling and one that was lapped,” said Dichter. “You can easily sense any remaining tight or loose spots in the bore. The diameter uniformity and roundness of the honed bore are superb. The lap also feels different in a honed bore.”
In competitive shooting where winning scores may be separated by thousandths of an inch, a few millionths of an inch improvement in the uniformity of a Pac-Nor barrel may make a big difference for a skilled shooter. For more information, visit www.sunnen.com or contact:
Sunnen Products Company
Mr. Bob Davis
Global Communications Mgr.
Sunnen Products Company
Tel: 314-781-2100
bdavis [at] sunnen.com
About Pac-Nor Barreling Inc.
Pac-Nor Barreling is a true custom manufacturer catering to bolt-action rifle shooters. The company’s principle markets are law enforcement, military, competitive shooters and hunters. Started in 1984 by avid shooter and company President Chris Dichter, Pac-Nor is now in its second generation under his son, Casey. In addition to barrel manufacturing, the shop will install the barrel on a customer’s action, or add features such as muzzle brakes or fluting on bolts and barrels etc.
The shop runs two shifts per day. A day shift of ten people produces 30-40 custom barrels of different calibers in 416R stainless or chrome-moly steel. A night shift of three people produces one type of barrel — about 50 AR-15 barrels per day for a rifle OEM.
Geissele Automatics manufactures a line of two-stage triggers favored by top Service Rifle, High Power, and 3-Gun shooters. Geissele now offers a variety of trigger models for both large-pin and small-pin lowers, with pull weights from 1.8 lbs to 6.0 lbs. You select the Geissele trigger with the appropriate first and second stage pull for your discipline (refer to chart below for trigger model specs).
Video Shows Geiselle Trigger Installation in AR15
Our friend Gavin Gear of UltimateReloader.com has crafted a video showing how to install a Geissele National Match Trigger in an AR15. This video covers installation of the trigger assembly, the trigger guard, the safety selector lever assembly, and the pistol grip.
AR15 Trigger Installation Video
Follow-Up Video for AR10 Trigger Install
Gavin recently released a follow-up video which covers the installation of a Geissele Super Dynamic Trigger in an AR10. The procedure is mostly the same as for the AR15, but this video also covers removal of the AR10 factory trigger, so it’s worth watching. You may want to turn the volume down on your computer’s speakers before playback. CLICK HERE for Geissele Trigger Instruction Manual
Here is Ernie Bishop’s pride and joy, a specialty pistol nicknamed “Batman” because the black carbon-fiber stock looks like the Batmobile. This is one sophisticated handgun. Complete with scope, the Batman pistol weighs under 7.5 pounds, thanks to the ultra-light stock. The carbon stock is 6 inches wide at the fore-end, yet weighs just one pound. Ernie tells us: “This gun shoots amazing and is easy to shoot especially with my SEB MAX Rest.” Ernie adds, “The gun will soon also have a field-usable rear-grip stock so I can shoot it prone from a bipod as well.”
The Batman pistol is chambered for the 6mm “Long Dasher”, a 6mm 40°-shouldered variant of the 6.5×47 Lapua. Ernie loads Berger 105gr Hybrid bullets pushed by Hodgdon H-4350 powder.
Gun Specifications The gun, crafted by Eric Wallance of Nawaka Firearms, features an XP-100 action, Jewell trigger, and 15″-long, Brux 1:8″-twist barrel with aluminum muzzle brake. Interestingly, this gun does not have a traditional recoil lug. Instead, gunsmith Wallace milled out a lug from the bottom of the XP-100 action to save weight. On top of the action, the rig carries a Sightron Inc S-III 6-24X56mm scope in Kelbly rings on a custom +20 MOA rail.
Long Dasher Wildcat
Shown at right is a “Long Dasher” 40° wildcat created by Forum member Sunbuilder. This is very similar to Ernie Bishop’s chambering, though there may be small variations related to reamer design (such as freebore). Sunbuilder’s 6-6.5×47 Improved (aka “Long Dasher”) reamer was made by Dave Kiff of Pacific, Tool & Gauge. This wildcat cartridge adds about 2.0 grains capacity to the 6.5×47 necked down to 6mm. The case certainly is impressive with that 40° shoulder. We’re just waiting for the tactical guys to starting run this improved cartridge with its original 6.5mm bore.
Here are three FIVE-shot groups at 500 yards, shot by Ernie’s Batman pistol:
With barrels, one wonders “Can a little more length provide a meaningful velocity gain?” To answer that question, Rifleshooter.com performed an interesting test, cutting a .308 Win barrel from 28″ all the way down to 16.5″. The cuts were made in one-inch intervals with a rotary saw. At each cut length, velocity was measured with a Magnetospeed chronograph. To make the test even more interesting, four different types of .308 Win factory ammunition were chronographed at each barrel length.
Test Barrel Lost 22.7 FPS Per Inch (.308 Win Chambering)
How much velocity do you think was lost, on average, for each 1″ reduction in barrel length? The answer may surprise you. With a barrel reduction from 28″ to 16.5″, the average speed loss of the four types of .308 ammo was 261 fps total. That works out to an average loss of 22.7 fps per inch. This chart shows velocity changes for all four ammo varieties:
Summary of Findings: The average velocity loss per inch, for all four ammo types combined, was 22.7 FPS. By ammo type, the average loss per inch was: 24.6 (Win 147 FMJ), 22.8 (IMI 150 FMJ), 20.9 (Fed GMM 168gr), and 22.5 (Win 180PP).
Interestingly, these numbers jive pretty well with estimates found in reloading manuals. The testers observed: “The Berger Reloading manual says for the 308 Winchester, ‘muzzle velocity will increase (or decrease) by approximately 20 fps per inch from a standard 24″ barrel’.”
How the Test Was Done
The testers described their procedure as follows: “Ballistic data was gathered using a Magnetospeed barrel mounted ballistic chronograph. At each barrel length, the rifle was fired from a front rest with rear bags, with five rounds of each type of ammunition. Average velocity and standard deviation were logged for each round. Since we would be gathering data on 52 different barrel length and ammunition combinations and would not be crowning the barrel after each cut, we decided to eliminate gathering data on group sizes. Once data was gathered for each cartridge at a given barrel length, the rifle was cleared and the bolt was removed. The barrel was cut off using a cold saw. The test protocol was repeated for the next length. Temperature was 47° F.”
CLICK HERE to Read the Rifleshooter.com Test. This includes detailed charts with inch-by-inch velocity numbers, multiple line charts, and complete data sets for each type of ammo. Rifleshooter.com also offers ballistics graphs showing trajectories with different barrel lengths. All in all, this was a very thorough test by the folks at RifleShooter.com.
Much Different Results with 6mmBR and a Longer Barrel
The results from Rifleshooter.com’s .308 barrel cut-down test are quite different than the results we recorded some years ago with a barrel chambered for the 6mmBR cartridge. When we cut our 6mmBR barrel down from 33″ to 28″, we only lost about 8 FPS per inch. Obviously this is a different cartridge type, but also our 6mmBR barrel end length was 5″ longer than Rifleshooter.com’s .308 Win start length. Velocity loss can be more extreme with shorter barrel lengths (and bigger cartridges). Powder burn rates can also make a difference.
In our Shooters’ Forum, you’ll find a lengthy thread about accuracy problems with a Savage LRPV, chambered in 6mmBR. The gun would repeatedly split groups at 100 yards, and at 300 yards, the “flyers” would open up the groups to 1.5 MOA or larger. Interestingly, the factory test target (at right) showed a split group — not a good sign.
The book contains many interesting feature stories. A fascinating article by Garry James, 
The gun, crafted by Eric Wallance of Nawaka Firearms, features an XP-100 action, Jewell trigger, and 15″-long, Brux 1:8″-twist barrel with aluminum muzzle brake. Interestingly, this gun does not have a traditional recoil lug. Instead, gunsmith Wallace milled out a lug from the bottom of the XP-100 action to save weight. On top of the action, the rig carries a Sightron Inc S-III 6-24X56mm scope in Kelbly rings on a custom +20 MOA rail.
