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.
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Today, AR-platform rifles are hugely popular. Dozens of manufacturers sell AR-type rifles, in a wide variety of configurations and calibers. But before there were M16s and AR-15s, ArmaLite produced a 7.62×51 caliber rifle, the AR-10. Yes before there were millions of 5.56 black rifles, there was a .30-caliber big brother with reddish-brown furniture. Invented by Eugene (‘Gene’) Stoner for the Armalite company in the late 1950s, this is the father of all of today’s AR-platform rifles. Way ahead of its time, this remarkable, select-fire battle rifle weighed just 7.25 pounds as first developed.
If you’re curious about the AR-10, in this video, Jerry Miculek puts an original 1957-vintage AR-10 through its paces on the range. This extremely rare, early-production rifle was provided by Mr. Reed Knight and the Institute of Military Technology. (The gun in the video was actually produced in the Netherlands under license, see video at 4:40.) This AR-10 is the direct ancestor of the AR-15, M16, and many of the modern sporting rifles that we use today.
The AR-10 was slim and light, weighing in at around 7 pounds. Some folks might argue that the original “old-school” AR10 is actually better that some of today’s heavy, gadget-laden ARs. The AR-10’s charging “lever” was under the carry handle — that made it easier to manipulate with the gun raised in a firing position.
You’ll notice there is no “forward assist”. Inventor Gene Stoner did not believe a separate “bolt-pusher” was necessary. The forward assist was added to solve problems encountered in Viet Nam. Some critics say the forward assist “only takes a small problem and makes it a big problem.” For today’s competition ARs (that are never dragged through the mud) the forward assist probably is superfluous. It is rarely if ever needed.
Note also that the handguards are fairly slim and tapered. Today, six decades after the first AR-10 prototypes, we are now seeing these kind of slim handguards (made from aluminum or lightweight composites) used on “full race” ARs campaigned in 3-gun competition.
History of the AR-10
The AR-10 is a 7.62 mm battle rifle developed by Eugene Stoner in the late 1950s at ArmaLite, then a division of the Fairchild Aircraft Corporation. When first introduced in 1956, the AR-10 used an innovative straight-line barrel/stock design with phenolic composite and forged alloy parts resulting in a small arm significantly easier to control in automatic fire and over one pound lighter than other infantry rifles of the day. Over its production life, the original AR-10 was built in relatively small numbers, with fewer than 9,900 rifles assembled.
In 1957, the basic AR-10 design was substantially modified by ArmaLite to accommodate the .223 Remington cartridge, and given the designation AR-15. ArmaLite licensed the AR-10 and AR-15 designs to Colt Firearms. The AR-15 eventually became the M16 rifle.
AR-10 photos from Arms Izarra, a Spanish company specializing in de-militarized, collectible firearms. Interestingly, this particular AR-10 was produced in the Netherlands under license.
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Do you have some old, tired brass that needs a thorough cleaning — inside and out? Consider using an ultrasonic cleaning machine. When used with the proper solution, a good ultrasonic cleaning machine can quickly remove remove dust, carbon, oil, and powder residue from your cartridge brass. The ultrasonic process will clean the inside of the cases, and even the primer pockets. Tumbling works well too, but for really dirty brass, ultrasonic cleaning may be a wise choice.
Our friend Gavin Gear recently put an RCBS Ultrasonic cleaning machine through its paces using RCBS Ultrasonic Case Cleaning Solution (RCBS #87058). To provide a real challenge, Gavin used some very dull and greasy milsurp brass: “I bought a huge lot of military once-fired 7.52x51mm brass (fired in a machine gun) that I’ve been slowly prepping for my DPMS LR-308B AR-10 style rifle. Some of this brass was fully prepped (sized/de-primed, trimmed, case mouths chamfered, primer pockets reamed) but it was gunked up with lube and looking dingy.”
UltimateReloader.com Case Cleaning Video (7.5 minutes):
Gavin describes the cleaning exercise step-by-step on UltimateReloader.com. Read Gavin’s Cartridge Cleaning Article to learn how he mixed the solution, activated the heater, and cycled the machine for 30 minutes. As you can see in the video above, the results were impressive. If you have never cleaned brass with ultrasound before, you should definitely watch Gavin’s 7.5-minute video — it provides many useful tips and shows the cleaning operation in progress from start to finish.
The RCBS ultrasonic cleaning machine features a large 3-liter capacity, 60 watt transducer, and 100 watt ceramic heater. The RCBS ultrasonic machine can be found under $140.00, and this unit qualifies for RCBS Rebates ($10 off $50 purchase or $50 off $300.00 purchase). RCBS also sells 32 oz. bottles of cleaning concentrate that will make up to 10 gallons of Ultrasonic Solution.
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We know many readers have been searching high and low for components and high-quality ammunition, particularly for popular chamberings such as the .308 Winchester. Well Santa delivered something nice for you .308 shooters. Bullets.com received a large shipment of Norma-brand Tac .308 ammo. This is good stuff — Norma brass loaded with a quality 150gr Norma FMJ bullet. This Tac-308 ammo is now in stock and On Sale for $53.50 for fifty (50) rounds at Bullets.com. If you can find this elsewhere, you’ll pay $65.00 or more per box. And remember, you’ve got quality Norma brass that will last for many reloadings after the ammo is fired. When you consider the value of the brass for reloading, this deal is even more attractive.
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The Civilian Marksmanship Program (CMP) is showing quantities of M118LR 7.62×51 for sale, stock number 4C762M118LR-240. This is quality ammo, manufactured by Federal. We believe that it is loaded with 175gr Sierra Match bullets, but you should call to confirm that. Packaged in 240-rd cans, the CMP’s M118LR ammo costs $275.00 for 240 rounds (that works out to roughly $1.15 per round). If you need 7.62×51 ammo for your M1A, or tactical bolt gun, this should fit the bill.
Nosler, Inc. has acquired Silver State Armory (SSA), an ammunition and cartridge brass manufacturer in Washington state. Nosler’s goal in taking over SSA’s product line and manufacturing capacity is to increase production in response to the current high demand for ammunition and reloading components.
According to Nosler’s President/CEO, Bob Nosler: “The Silver State acquisition provides a strategic opportunity for Nosler to increase capacity at this unique time in the history of our industry.”
Located in Packwood, Washington, Silver State Armory makes a wide variety of ammunition, loaded in its own cartridge brass with a variety of name-brand bullets (such as Nosler, Barnes, and Sierra). Primary ammo types are 5.56mm/.223 Rem, 6.8 SPC, and 7.62×51 ammo. SSA’s catalog also lists cartridge brass for: 6mm PPC, 5.56x45mm, 6.8mm SPC, .243 WIN, .260 REM, 7.62x51mm, and .308 Win, .270 Win, and .300 Win Mag.
Founded in 1948, Nosler is a family-owned company located in Bend, Oregon. Nosler, best known for its Partition® and Ballistic Tip® bullets, manufactures premium ammunition as well as component bullets and brass. Nosler also produces semi-custom rifles for domestic and international customers. In March of 2012, Nosler became ISO 9001:2008 certified.
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Many visitors to the site ask us, “I’ve got a .223 and .308. What will a 6mmBR Norma (6BR) give me that I’m not getting already?” Well first you will probably average consistently smaller groups than your current .223 or .308 rifle (assuming the 6BR has a quality barrel and trigger). A good .308 Winchester can be superbly accurate, no question about that, but the lesser recoil of the 6BR works in the shooter’s favor over a long string of fire. Even with a Rem 700 or Savage action factory action, a 6BR with a benchrest stock, premium barrel, and a high-quality chambering job should deliver 5-shot groups in the high twos to mid-threes, provided you do your job. We have one 6BR rifle that shoots Lapua factory-loaded 6BR ammunition in the low twos and high ones. That’s exceptional, we admit, but it still shows how the 6BR is an inherently accurate cartridge, even with factory loads.
Compared to a .223, the 6BR offers a much better selection of high-BC projectiles, and will deliver considerably more power on the target. Compared to the .308 shooting 168gr MatchKings, a 6BR shooting 105-107gr bullets offers better ballistics all the way out to 1000 yards. Plus, for most people, the 6BR is just easier to shoot than a .308. Recoil is less than half of the .308 cartridge. Both the .308 and 6BR chamberings offer good barrel life, but the 6BR uses 15-18 grains less powder, saving you money. Here’s how the 6BR stacks up vs. a number of popular calibers:
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Experienced .308 shooters know that the 168gr Federal Gold Medal match ammunition often performs superbly in both factory and custom .308 Win rifles. We’ve seen this stuff shoot 1 MOA in an FN-FAL and close to half-MOA in a GAP tactical rifle. We won’t make any promises, but the reputation of this ammo speaks for itself. Right now, Champion Shooters Supply has Federal GM308M 168gr factory ammo for just $20.00 per box of 20 rounds. That’s 56% off Champion’s regular price, and way below what this ammo normally costs. Loaded with the 168gr Sierra MK BTHP bullet, this stuff is very high grade ammo at a very attractive price. NOTE: If you want it, order soon. Champion states: “Sale Supply is limited, once we run out we cannot continue this special price.”
Story sourced by Edlongrange.
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Applied Balllistics LLC, run by Bryan Litz, has just released new .308 Winchester Tactical Ammunition. This new ammo employs a brand-new 175gr “Tactical OTM” bullet from Berger Bullets. This new projectile is unique in that it was designed to “fly right” even at transonic and subsonic speeds. The new 175gr bullets are loaded to magazine length (2.800″) in new Lapua brass, so the ammo will fit all popular detachable box magazines in tactical bolt guns and gas guns. Bryan recommends a 1:13″ (or faster) twist barrel.
New Tactical Ammo Has Individually-Weighed Charges and Low ES
Unlike most “factory ammo”, Bryan’s new Tactical Ammo features individually weighed charges. That’s right — the charge for each and every round is weighed before it goes in the case. As a result, the new ammo typically delivers Muzzle Velocity (MV) Standard Deviation (SD) under 10 FPS (for 10 shots). That’s a low number, on a par with quality handloads. Bryan has shot this ammo at 1000 yards through a LaRue OBR AR10-type rifle. The ammo shot under one MOA at 1000 yards. Another benefit of the weighed charges is that this allows the use of high-quality extruded (stick) powders. The stick powders are known to deliver great accuracy while being consistent through a wide temperature range.
Berger’s NEW .30 Caliber 175gr Tactical OTM Bullet
This bullet was designed by Berger Ballistician Bryan Litz specifically to optimize performance of the M118LR class of ammunition. The design objectives were to maximize BC while staying within the 2.800” COAL for magazine feeding, and the requirement for the bullet to remain stable through transonic speeds. All of these design objectives were achieved, according to Bryan. The bullet has a length-tolerant tangent ogive shape, so it is less sensitive to seating depth than secant-ogive bullets.
The BC of this bullet is 7% higher than the 175 grain Sierra MatchKing currently used in most M118LR ammunition, and 2% higher than the Hornady 178 grain option. The average G1 BC of the Berger 175gr Tactical bullet is 0.510 from 3000 to 1500 fps. The G7 BC is 0.259, and is a more accurate representation of this bullets performance over a wide range of speeds. (CLICK HERE to read about G1 vs. G7 BC.)
The Berger 175gr Tactical OTM bullet requires a minimum twist rate of 1:13″ to be stable from the muzzle. Transonic stability was verified from a 20″-barreled LaRue OBR with a 1:11.25″ twist.
Early Tests Show Bullet Shoots Great — Report by Robert Whitley
Robert Whitley got a box of early-run 175gr Tactical bullets. He says they shoot great in his own handloads: “I just received some of the new Berger .30 cal 175gr Tactical OTM (Open Tip Match) bullets. Wow — what great bullets for the .308 Winchester! I did some range testing and these things really shoot! As you can see below, I had a 5-shot group around 0.2″ and, then, shooting prone, I produced a 20-shot group that just tore out the X-Ring.” (NOTE: these targets were shot with Robert’s handloads, not the Applied Ballistics pre-loaded ammo.)
While the words “Open Tip Match” might lead one to believe it has a large open tip, this BTHP bullet actually has a small meplat. Robert suspects that, for this bullet’s potential tactical and military applications, it was felt the words “hollow point” should be avoided in favor of “open tip”.
Bullets Are Positioned Optimally When Loaded at 2.800″ Mag Length
These bullets were also made to be loaded at magazine feeding length in the .308 Winchester (2.800″ OAL). Robert reports: “When loaded at a 2.800″ OAL length, the bullets sit perfectly in the neck of the .308 Winchester, with the full bearing surface of the bullet up in the neck of the case, and the junction of the boat tail and bearing surface of the bullet just forward of the junction of the neck and shoulder of the case.”
If you are going to shoot these bullets and expect them to be supersonic the whole way, a 1:13″ or faster twist is recommended, and if you are going to run them at velocities where they might be subsonic/transonic, Bryan confirmed they’ll work in 1:11.25″ twist barrels. Robert notes that his company, AR-X Enterprises, carries 1:11.25″ twist Bartlein .30 Cal barrels as a regularly-stocked item in both the M24/M40/Rem Tactical contour and the Remington Heavy Varmint/Sendero contour.
Whitley concludes “This is a great offering by Berger Bullets”. While the bullets can be purchased through Berger or Berger’s dealers, the new Applied Ballistics’ loaded ammo should be ordered through Bryan’s website. The price is $40 (plus shipping) for 20 rounds.
CLICK HERE to order through the Applied Ballistics secure shopping cart.
Disclosure: Applied Ballistics LLC advertises Bryan Litz’s Ballisitics Book on this site.
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Remington has released a new sniper rifle that is WAY different than anything offered from a major American gunmaker, although it shares features pioneered by match-rifle builder Gary Eliseo and others. The new Remington Modular Sniper Rifle (MSR™) features a beefy new titanium receiver with the ability to handle multiple chamberings up to .338 Lapua Magnum. The MSR was designed from the ground up as a switch-barrel rig, with a floating handguard, and folding, adjustable buttstock.
The whole system is modular. By exchanging bolt-face, barrel, and magazine, the gun can switch from .308 Win (7.62×51), to 300 Win Mag, to .338 Norma Mag, and to .338 Lapua Mag. All calibers are available in four barrel lengths: 20″, 22″, 24″, 27″. Barrels are designed to be rapidly interchanged. The trigger is an X-Mark Pro, user-adjustable from 2.5 to 4.5 pounds.
This rifle is Remington’s entry into the competition for the new SOCOM Precision Sniper Rifle (PSR). Big bucks are at stake. The SOCOM PSR contract is potentially a seven-figure deal for Remington. According to Tactical-Life.com, “Remington’s new MSR is so new and so unique that the entire rifle is patent pending. Everything from the triangular-shaped, three-lug titanium action with a 60° bolt throw to the side-folding modular stock was developed specifically for this [SOCOM] solicitation.”
Remington claims the gun delivers good accuracy at ultra-long ranges. Using .338 Lapua Magnum ammo, Remington says its MSR will hold 1 MOA vertical at 1500 meters (1641 yards). While we don’t like the buttstock assembly much (looks like something out of the Transformers movie), it is clear that Remington has done some out-of-the-box thinking with this new rifle. The MSR employs some features that have proven successful with “space-gun” match rifles, such as a tubular, floating handguard, and metal sub-chassis.
To learn more about the Remington MSR, and see a video of the rifle in action, visit RemingtonMilitary.com.
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