Forum member Brian V. (aka “Carbide”) wanted a new look for his “modern sporting rifle”. He was tired of looking at black plastic (or FDE, OD green) and aluminum components on his AR15. So he decided to fit wood “furniture” on the rifle. He ordered a wood butt-stock and fore-arm set made by Lucid, but he didn’t like the two-piece fore-arm of the Lucid stock set. He decided he could build something better than the commercially-available, Lucid-made wood fore-arm.
So Brian took his existing AR tubular fore-arm and epoxied a walnut sleeve to it. With a lathe, Brian then turned the walnut sleeve to his desired dimensions: 2.250″ diameter in back and 2.200″ diameter in front, so there’s a little taper. Brian says “I could have gone a little thinner.” The wood fore-end was then sanded and stained to match the Lucid-made rear section. Brian says “the stain is not quite a perfect match, but but it looks a lot better.”
Berger Bullets has just announced a new 6.5 mm (.264 caliber) 130gr Hybrid projectile. Optimized for magazine-length seating (and AR10-friendly), the new 130gr bullets should be ideal for tactical comps and the PRS series. We expect this new bullet to work great when loaded in modern mid-size cartridges such as the 6.5×47 Lapua and 6.5 Creedmoor. Berger’s new 6.5mm 130gr Match AR Hybrid OTM Tactical bullet (could Berger come up with a longer name?) will soon be released to the public. Berger says this new 130-grainer is the first of many new bullet designs to be introduced in the next few years. Here is a run-down on the new bullet from its designer, Bryan Litz of Applied Ballistics.
NEW 130gr Hybrid — Behind the Design
by Bryan Litz, Berger Chief Ballistician
Intelligent bullet design and selection begins with an understanding of application constraints. For bullets that will be used in unlimited rifles, there are few constraints and performance can truly be maximized. However, many shooting applications have realistic constraints such as magazine feeding of loaded rounds. In constrained applications, you need to ask the question: “What’s the best bullet that will work within the constraints of my shooting application?”
The new Berger 6.5mm 130 grain AR Hybrid OTM Tactical bullet is specifically optimized for maximum performance in magazine-length ammo.
6.5mm cartridges are the second most common cartridges used by top shooters in many of the Precision Rifle Series (PRS) matches, with 6mm being the most common. These kinds of tactical matches all have stages that require repeating rifles — either AR-10 platforms or bolt guns — so magazine feeding is a must. Recognizing that Berger did not have an option that was truly optimized for this particular application, we went to work and the latest 6.5mm Hybrid is the result.
SUMMARY
The new Berger 6.5mm 130 grain AR Hybrid OTM Tactical bullet is specifically optimized for use in loaded ammo with COAL constraints for magazine feeding. This bullet maximizes overall performance through BC as well as achievable muzzle velocity in mid-capacity 6.5mm cartridges fed from AR-length magazines.
What makes this bullet optimal for magazine length ammo? To start with, the nose of the bullet is constrained in length so that when it’s loaded to mag length in 6.5mm cartridges such as the 6.5mm Creedmoor, 260 Remington and 6.5×47 Lapua, the nose of the bullet won’t be pushed below the case mouth. This can be an issue with some of the heavier 6.5mm bullets like the 140s. Furthermore, the hybrid ogive design is not sensitive to jump distance like some other designs such as the VLD.
Another consideration of length-constrained ammo is how much of the bullet is pushed down into the case. The inside of the case is for powder, and the more space you take up with bullet, the less powder you can fit in. Less powder means less total energy available, and muzzle velocity is depressed. A bullet weight of 130 grains is an optimal balance between external ballistic performance (BC) and internal case capacity considerations which translate into muzzle velocity. Further to this objective, the AR Hybrid has a minimal air gap in the front of the nose, which allows the bullet to have an even shorter OAL. When dealing with length-constrained designs, you need to pack as much bullet into as little length as possible< to optimize overall performance. Another advantage of making the bullet shorter is that stability, including transonic stability, is improved.
Although this design is length-constrained, the combination of a hybrid ogive and 7 degree Boat Tail produce a very respectable G7 form factor of 0.920 which is within 1% of the popular 6mm 105 grain Hybrid. See below for full live fire ballistic performance data.
The 6.5mm 130 grain AR Hybrid will be barely stable from a 1:9″ twist, and reaches full stability from a 1:8″ twist which is common for many 6.5mm rifles. Visit the Berger Bullets twist rate calculator to get more detailed stability information on your specific barrel twist, muzzle velocity and environment.
Cartridge Selection for Magazine Length Constraint — Advanced Analysis
The trend to smaller calibers in magazine-fed rifles is happening for a very good reason. For a .308 Winchester round, you only have 2.37 calibers of nose length available for the bullet to protrude from the case. Such a short nose will have relatively high drag for the caliber. By contrast, smaller calibers such as 6.5mm and 6mm have proportionally more length available for the nose to protrude from the case and still fit in the same COAL constraint. Proportionally longer noses mean lower drag. Proportionally longer bullets mean higher sectional density. Combine an elevated sectional density with lower drag, and you get higher BC bullets. For example, consider a 175 grain .30 caliber bullet commonly used in .308 Winchester M118LR-type ammo. These 175 grain bullets have G7 BCs in the neighborhood of .243 to .260. Neck the .308 down to 6.5mm (260 Remington) or 6mm (.243 Winchester) and now look at the BCs of the bullets available in these calibers which work within the same magazine length constraint. The 6.5mm 130 grain AR Hybrid has a G7 BC of 0.290, and the 6mm 105 grain Hybrid has a G7 BC of 0.278 — both of which are higher than the .30 cal 175 grain bullet BC. Furthermore, you get hundreds of feet per second more velocity with the necked-down cartridges as well.
All of the above translates into higher hit percentage. See the caliber comparison chart below* which is an excerpt taken from the book: Modern Advancements in Long Range Shooting which addresses this and many other topics in even more detail.
*The Weapon Employment Zone (WEZ) analysis shown above is for a 1000-yard shot on a standard IPSC silhouette in an uncertain environment having: +/- 2 mph wind, +/- 1 yard range, Muzzle Velocity SD of 10 fps, and a rifle shooting 1 MOA groups.
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By Dennis Santiago Competition teaches you things. Compared to loading for benchrest bolt guns, producing ultra-reliable and accurate ammo for tight-chambered, semi-auto .308 target rifles requires a different approach to case prep. Smoothness of operation is much more important in a field course gun. Reliability trumps everything (even case life) for these types of guns.
In the photo below, there’s a Redding small base body die for bumping the shoulder and making sure the case body is at SAAMI minimum. This body die is not just nice to have. It is vital. There are also a full-length sizing die and a Lee Collet neck-sizer in that turret holder. One or the other gets used after the body size die depending on what rifle the ammo will be used in. The semi-auto rounds always go through the full-length sizing die. After that comes trimming and finally cleaning — then loading can begin. The cases are trimmed using a Gracey trimmer so everything’s the same each and every time. I use an RCBS Competition Seater Die to seat the bullets. One nice feature of this RCBS die is the open side slot that allows you to place bullets easily.
It’s a long path methodology but uniformity is accuracy. More important for safety, controlling “stack-up” errors in the system solution is how one achieves reliability. The chamber-hugging philosophies of benchrest bolt guns do not apply well to AR-10s. Like most things, the right answer is context-dependent. Success is about accepting and adapting.
Dennis Talks About Using a Semi-Auto in Tactical Competitions
I have succumbed to the Dark Side — deciding to put an AR-10 together. For tactical competitions you want a bolt gun most of the time but there are times the course of fire favors the use of a semi-auto. I was using an M1A that gives me 0.75 MOA performance but I heard people were getting almost bolt-gun-level, half-MOA accuracy out of their AR-10s — so I wanted to see if that was really achievable. A quarter-MOA difference in accuracy potential may seem tiny in practical terms but it will make a difference in competition. In a match, the difference between 3/4-MOA and 1/2-MOA can alter your hit probability on a small target by 20-30%.
The AR platform also lets you tinker with triggers, stock ergonomics and muzzle brakes that help in managing the dynamics of a long distance shot better. Well I found out you can get the incremental accuracy but there’s more work to do to get the same reliability. Being a curious sort, it’s worth it to me to explore it. It’s a far cry from as-issued M-1 shooting with whatever HXP is handy. This is definitely swimming in the deep end of the pool.
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The AR-10 was designed to handle the 7.62×51/.308 Winchester and other .308 “family” cartridges such as the .243 Win and .260 Remington. Our friend Dennis Santiago recently put together an AR-10 to shoot the accurate .260 Rem cartridge. Here is his initial report:
AR-10 Platform Chambered for .260 Remingtonby Dennis Santiago
I was very curious to see how the .260 works in the AR-10 compared to a .308. I’ve always thought about chambering a bolt gun in .260 but before doing so I thought it’d be good to try it using a less expensive entry point. With an AR platform’s easy interchanging of barrels, it seem like the best way to test out the .260 Rem chambering. So far, it’s most impressive.
DPMS LR-308 in .260 Remington getting function cycle tuned and zeroed
I took the AR-10-type .260 Rem a step closer to being ready for matches yesterday. The first order of business was to confirm which buffer spring to use with both the 123 grain and 140 grain bullet loads. My .260 Rem loads, on average, are using 4-5 grains less powder than the .308 loads. In a semi-automatic action that means less gas/energy to work the mechanics. The solution in an AR-10 platform is to either cut coils in the .308 spring or use a weaker AR-15 buffer spring; yup they are not the same. In this case, a CS flat spring for the AR-15 did the trick.
I also put a very nice NightForce Benchrest 12-42x56mm scope that came via friend Mark Gravitt on it and got zeros. This scope’s 1/8th MOA clicks are nice. The AR-10 had previously mounted a NightForce F1, a more “field tactical” 3-15X system. This 12-42X scope now sets this gun up as more of a target cannon. Field of view is limited when your minimum magnification is twelve. Maybe I’ll put an auxiliary red dot on it just to find the target.
Pet Loads: H4350 and Lapua 123gr Scenars Comment by Daily Bulletin Editor
Over a two-year period, this Editor put a lot of rounds through a .260 Remington. I did a ton of load testing with that Savage-actioned rifle (before it was rebarreled as a 6mmBR Norma). I tried two dozen load recipes with five different powders and bullets ranging from 100 grains to 142 grains. Hodgdon H4350 was my “go-to” powder. As many 260 Rem shooters have discovered, H4350 is a winner in the .260 Rem. This propellant delivered the lowest ES in my rifle and nothing beat H4350 for consistent accuracy with bullets in the 120-140 grain range. My most accurate load was with Lapua 123gr Scenars, pushed by H4350 and CCI 250 primers. The 123gr Scenars worked well jumped as well as seated into the lands. Best accuracy, in my 24″-barreled .260 Rem, was right about 2950 fps. Other powders work well, but H4350 is a very good choice for the .260 Remington (as well as the smaller 6.5×47 Lapua cartridge).
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For many cartridge types, Hornady Superformance ammunition provides enhanced velocity compared to some other types of factory-loaded ammo. However, Hornady has found that there may be issues when Superformance ammo is shot in gas-operated guns with barrels under 20″, or with barrels fitted with suppressors. This is because the gas returning from the barrel port may cause the bolt to begin unlocking prematurely. Hornady has published the following information concerning the uses of Superformance ammo in direct impingment and gas piston self-loading rifles.
Internal Ballistics of Superformance Ammo in Semi-Auto Guns
Superformance™ ammunition is tested and is safely within SAAMI pressure guidelines. Gas operated (direct impingement or gas piston) firearms are perfectly safe to use with Superformance ammunition. However, Hornady ballisticians have conducted testing with a variety of guns (including guns equipped with suppressors), and our findings conclude that some systems work far better with Superformance ammunition than others.
It is recommended that to get the best functioning with Superformance ammunition in gas operated/gas piston semi-automatic or select fire guns, rifle length gas systems with 20 inch or longer barrel lengths are best for reliable firing and extraction. Any other configuration — particularly shorter barrels/gas systems — are best served with the installation of an adjustable gas system, ESPECIALLY if a suppressor is to be installed.
Due to the longer duration of peak pressure produced by Superformance, the post peak/declining port pressure at common carbine and mid-length gas port locations is still higher than that produced by standard propellant. This has a tendency to flood the system with a larger volume of gas, at a higher velocity, that tries to open the bolt of the gun too fast. It’s a timing issue. The cartridge case is still swollen from the application of pressure during firing while the gun is simultaneously trying to extract the cartridge case before it has had an opportunity to settle back to its original size, or more simply: the gun is still in the process or firing while it’s trying to extract the cartridge case.
If the firearm and the ammunition are not in sync, there can be what is commonly identified as “pressure signs” on the cartridge case. This is exhibited by the movement/marring of the head of the cartridge case, cratered primers, flat primers, ripped or ruptured cartridge cases, “popped primers”, and/or any combination of these effects. If any of these “pressure signs”; are apparent, stop firing immediately. If an adjustable gas system is installed, it is advisable to reduce the amount of gas flowing through the system by closing the gas port until the gun operates correctly.
With the installation of an adjustable gas system, gas pressure can be metered to a point that enough gas is applied to open the bolt, but at a slower rate to allow the cartridge case to return to its original diameter prior to the movement of the bolt, and thus allow for proper extraction.
Pressure VS Gas Port Location
Due to the longer duration of peak pressure produced by Superformance™, the post peak/declining pressure at common carbine and mid-length gas port locations is still higher than that produced by standard propellant. However, there is very little difference in port pressure between Superformance™ and standard propellants at the rifle length port location.
Superformance and Suppressors
The use of suppressors on rifles creates yet another dynamic in firearms design that is not commonly understood or communicated. Consider the suppressor on a firearm the same as a muffler on a car. The suppressor works as a filter for the gas (noise) that is escaping the barrel during firing. As a “filter”, it takes longer for the gas to leave the confines of the firearm, and thus, it creates back pressure. This back pressure, ESPECIALLY in a gas operated firearm forces an extensive amount of gas back through the firearm’s operating system that may create too much thrust too early during the firearm’s cycle of operation.
To counteract this back pressure, the use of an adjustable gas system is advised. By metering the gas system to ensure that it will cycle the firearm correctly and not flood the system with gas/pressure, the gun will work properly and will still benefit dramatically from the increased velocity potential of Superformance ammunition.
There were many semi-auto “tactical” rifles on display at MEDIA Day 2013, but one that caught our eye was the new MR762A1 LRP from Heckler & Koch (HK). The HK MR762A1 LRP (“Long Range Package”) looks similar to the H&K G28 rifle, Germany’s new Designated Marksman Rifle. But the G28 has a steel upper receiver, unlike the MR762A1, which evolved from the HK 417.
Bedecked with quad rails up front, this black and tan rifle screams “tactical”, yet it is surprisingly comfortable to shoot. The grip is comfortable in the hand and the thick rubber buttpad on the adjustable buttstock did a good job of mitigating recoil. Jason said the trigger was crisp and the gun was very accurate. With a gas-piston system (rather than direct gas impingement), this rifle runs very clean. The proprietary, polymer HK magazine worked perfectly with zero feeding issues. We liked these better than the metal mags we’ve tried on other makers’ AR10-type systems.
The MR762A1 is a direct descendent of the HK416/417 series, only in a semi-automatic rifle configuration developed for civilian users. The MR762A1 LRP employs the same HK proprietary gas piston operating system found on current HK rifles and carbines, using a “pusher” rod in place of the gas tube in the original M16/AR15/AR10 design. According to HK, the op-rod design “virtually eliminates malfunctions common to direct impingement gas systems since hot carbon fouling and waste gases do not enter the receiver area. The MR762A1 stays cleaner, reducing heat transfer to the bolt and bolt carrier, and drastically reducing wear and tear on other critical components.”
The MR762A1 uses the same 10- and 20-round translucent polymer box magazines made for the HK417; a 5-round magazine is also under development. Additional accessories and add-ons for the LRP variant of the MR762A1 include an ERGO Pistol Grip from Falcon Industries, the same Blue Force Gear sling used on the HK M27 IAR supplied to the USMC, and an OTIS cleaning kit. The rifle package, complete with one 20-rd mag and one 10-rd mag, is shipped ready to use with the scope attached in a 42″-long Model 1720 Pelican case.
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A “pimped-out” Turnbull Manufacturing TAR-10 (AR 10-platform) rifle shattered the all-time SHOT Show Auction record with a high bid of $136,024.00. Proceeds from the auction conducted last week will go to support the NSSF’s Hunting Heritage Trust. This unique Turnbull TAR-10, chambered in .308 Winchester, has features rarely seen on an AR-style rifle: color case-hardening, hand engraving, gold inlay, and select walnut “furniture”. The upper and lower are made from 8620 carbon steel that has been color case-hardened with the Turnbull bone charcoal process.
The gun has been elaborately engraved by Adams and Adams, with extensive gold inlay. The butt-stock, fore-end, and pistol grip are select fancy walnut.
“We did our best to make this a very special rifle and we had hopes of beating the all-time record of $83,025.00, but we never imagined the bidding would surpass $100,000 and then soar to more than $136,000.00,” commented Doug Turnbull.
“Our objective in creating the TAR-10 was to show that the AR platform is more than just a military rifle. We wanted to emphasize that these types of rifles can be made to look like any other custom rifle in terms of appeal,” commented Turnbull. The rifle, as sold, was equipped with a Zeiss 1.5-6x42mm Victory HT scope. Regular production Turnbull TAR-10 rifles will be the same as this special SHOT Show rifle minus the elaborate engraving and presentation-grade wood.
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Here’s a simple tool that may benefit you AR15 and AR10 shooters out there. The G&G Tools’ Bolt Cleaner and Polisher uses a radiused scraper with a cleaning pad to remove stubborn carbon from the tail of your AR bolts. The G&G Tool is offered in both a .223 version and a .308 version, both priced at $29.99. There is also a more basic (scraper only) unit for $19.99.
There are other ways to remove carbon (soaking in solvent and scraping with a knife), but G&G’s tools make the job quick and easy. Credit The Firearm Blog for finding this device. Watch the video below to see the tool in action.
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With a standard AR-15 we’ve never had problems with the standard coil-spring-equipped buffer system (other than the annoying spring noise). But with the AR-15’s big brother, the heavier-recoiling AR-10, an enhanced buffer system is welcome. A upgraded buffer won’t reduce recoil force, but it can soften the perceived recoil pulse, allowing the shooter to get back on target more quickly while reducing shooter fatigue over an extended string of fire.
Buffer Technologies of Jefferson City, MO, has introduced a new hydraulic buffer for AR-10-type rifles. Priced at $99.95, the hydraulic buffer weighs 0.38 pounds, has a 5.8-inch compression length, and fits AR-10s with full-length buttstocks. The buffer, crafted from black-oxided steel and black-anodized aluminum, is optimized for use with the .308 Winchester cartridge.
Buffer Technologies claims that its hydraulic buffer can help prevent failures of internal parts and optics by reducing shock and taming recoil. According to Rob Parham, Buffer Tech’s Military/LEO Sales Director: “Our new buffer makes a great gun even better, while protecting the valuable accessories on the firearm. This product is great in assisting target acquisition and allows for quicker follow-up shots.”
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The basic AR15, with upgrades to barrel, trigger, optics and “furniture” has evolved into an extremely effective varminter, chambered in .223 Rem, or a .20-caliber such as the 20 Practical. Hunters have also adapted the AR10 platform, with its ability to fire a .308 Winchester-sized cartridge, for use on deer and Elk. Now ArmaLite has “re-introduced” a handy, compact AR10 carbine that should be ideal for hog hunters.
The folks at ArmaLite received many requests for a lighter, more compact version of the AR10. Armalite responded: “We did a small limited run and we’re pushing its use as a varmint hunter… especially good against wild boars. One of our ArmaLite gunsmiths got the idea from some buddies in Texas who are using their Ts against the wild hogs. This AR-10(T) Carbine combines the light weight and compact size of the carbine with the accuracy of the Target Model.” This AR10(T) carbine features a 16″, 1:11.25″ twist barrel, fitted to a forged, flat-top receiver with built-in Picatinny rail. With a compact 37.5″ length, the gun weighs 8.6 pounds (3.9 kg). Included with the rifle are one 10-round mag, and one 20-round mag. MSRP is $1892.00.
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Defying its reputation as a stodgy, conservative organization, the IBS will allow AR-style rifles to compete in their own class at IBS benchrest matches next year. Both AR15-platform and AR10-platform rifles can compete in this new, provisional class.
This will NOT displace any of the current classes (e.g. Sporter, LV, HV, Unlimited), nor change any rules for current classes. The “AR Experiment” will last for one year and then the IBS will determine whether to make the class permanent. IBS President Jeff Stover stressed three points:
1. This is an experiment for a one-year trial.
2. Clubs MAY have an AR class, but they are not required to do so.
3. The IBS Nationals are NOT affected — there will be no ARs at any Nationals
The IBS has distributed proposed draft rules, and the IBS plans to adopt final rules on March 1, 2010. Here are some of the key proposed rules:
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Timney Triggers now offers a true drop-in trigger for the AR10 rifle platform, similar to Timney’s successful drop-in trigger for the AR15. The new AR-10 trigger is a self-contained, 100% drop-in unit that can be easily owner-installed (no professional gunsmithing required). The new trigger is a single-stage design with pull weight factory-set at 4 pounds. The trigger module installs using your rifle’s original hammer and trigger cross-pins. The MSRP is $234.95, but we expect the trigger to be available for $210 or so from other vendors.
The new trigger is solidly built and precision-machined. The housing is lightweight, 6061 T6 aluminum alloy, anodized for durability. The hammer is EDM-machined from S7 tool steel for superior hardness and impact resistence, and the hammer is Teflon + Nickel coated to provide greater lubricity and a smooth pull. Other components are EDM-cut from A2 tool steel, then heat treated to Rc 56-60 for longer service life. For more information on Timney Triggers, call (866) 484-6639, or visit TimneyTriggers.com.
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Proportionally longer noses mean lower drag. Proportionally longer bullets mean higher sectional density. Combine an elevated sectional density with lower drag, and you get higher BC bullets. For example, consider a 175 grain .30 caliber bullet commonly used in .308 Winchester M118LR-type ammo. These 175 grain bullets have G7 BCs in the neighborhood of .243 to .260. Neck the .308 down to 6.5mm (260 Remington) or 6mm (.243 Winchester) and now look at the BCs of the bullets available in these calibers which work within the same magazine length constraint. The 6.5mm 130 grain AR Hybrid has a G7 BC of 0.290, and the 6mm 105 grain Hybrid has a G7 BC of 0.278 — both of which are higher than the .30 cal 175 grain bullet BC. Furthermore, you get hundreds of feet per second more velocity with the necked-down cartridges as well.
Competition teaches you things. Compared to loading for benchrest bolt guns, producing ultra-reliable and accurate ammo for tight-chambered, semi-auto .308 target rifles requires a different approach to case prep. Smoothness of operation is much more important in a field course gun. Reliability trumps everything (even case life) for these types of guns.
Here’s a simple tool that may benefit you AR15 and AR10 shooters out there. The 
Defying its reputation as a stodgy, conservative organization, the IBS will allow AR-style rifles to compete in their own class at IBS benchrest matches next year. Both AR15-platform and AR10-platform rifles can compete in this new, provisional class.
