March 1st, 2015

Surprising Results in .223 Rem Barrel Cut-Down Velocity Test

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.

.223 Rem Cut-Down Test barrel UMC m855

READ RifleShooter.com 5.56/.223 Barrel Cut-Down Test Article.

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.”

CLICK HERE to Read the Rifleshooter.com Test. This includes detailed charts with inch-by-inch velocity numbers.

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.

Permalink Gunsmithing, Tech Tip 6 Comments »
March 1st, 2015

California Microstamping Requirement Upheld in Court

Californians may be relegated to shooting revolvers soon. On February 27, 2015, a Federal Judge in California over-ruled objections to a California state law requiring that all new semi-auto handguns have microstamping capability. In granting summary judgment to the State, Eastern District Judge Kimberly Mueller halted legal efforts to over-turn microstamping requirements for semi-auto pistols. Unless this District Court ruling is overturned on appeal, this Federal Court decision would effectively ban the sale or possession of most (if not all) new semi-auto handguns in the state.

Editor’s Comment: There is some hope however — the Calguns Foundations said counsel has already appealed the recent ruling to the Ninth Circuit Court of Appeals.

The ruling was issued in Peña v. Lindley, a Federal case that pitted California resident Ivan Peña and three other individual plaintiffs against Stephen Lindley, the chief of the California Department of Justice’s Bureau of Firearms.

At issue was California’s microstamping law, which was signed into law in 2007 by then-Gov. Arnold Schwarzenegger, but which only took effect in 2013. In the two years since the micro-stamping requirement went into effect, no manufacturer has made a new firearm that complies with the requirement. Both Smith & Wesson and Sturm, Ruger & Co., are not shipping their latest (post-2013 design) firearms into the California market because of the microstamping law. Opponents of the law argued that the microstamping requirment was, effectively, a de facto ban on all semi-auto pistols, since not one manufacturer has offered guns that comply with the law.

“This is about the state trying to eliminate the handgun market,” said Alan Gura, the lead attorney in Peña v. Lindley told Fox News last week. “The evidence submitted by the manufacturers shows this is science fiction and there is not a practical way to implement the law.”

The Peña v. Lindley case was argued at the trial court on December 17, 2013. Peña, gun manufacturers, and attorneys for the Second Amendment Foundation and Calguns Foundation argued that microstamping relies on impractical and unworkable technology. The plaintiffs argued that, if guns without the technology can’t be sold in California, and gun manufacturers can’t implement the technology, then the law functions as a de facto handgun ban that violates the Second Amendment.

The Calguns Foundation stated that the group is “disappointed that the district court sidestepped a clear violation of Second Amendment civil rights in its decision today. However, we are absolutely committed to litigating this case as far as necessary to reverse this incorrect ruling and restore the right to keep and bear modern handguns in the Golden State.”

Story based on report in Cheaper that Dirt Shooters’ Log.

Permalink News 8 Comments »
March 1st, 2015

Offset Scope Mount Helps Shooter with Vision Problem

offset scope base mountForum member Roy Bertalotto did a real nice off-set scope installation on a bolt gun to help a sight-challenged shooter. Roy explains: “A friend of mine shoots left-handed and has lost the sight in his left eye. I built him a scope mount so he can still shoot left-handed, but now use his right eye.” Roy’s fabrication work is impressive and we praise his efforts to help a fellow shooter stay in the game.

Roy bolted a plate to the existing scope rail on the top centerline of the Rem 700 action. This plate extends a few inches to the right. On the outboard end of the plate, Roy fitted a second scope rail, aligned with the bore. Weaver-based rings are then clamped to the outboard (right side) auxiliary rail.

offset scope base mount

offset scope base mount

offset scope base mount

Be Careful of Canting Issues with Offset Scope Installations
We’re pleased to see that Roy developed a solution for a shooter with an optical disability, but we want to stress that this is a specialized installation that can create some problems with point of impact shift if the gun is not maintained perfectly level. With the amount of horizontal offset (between the scope’s optical axis and the bore axis) built into this rig, if the rifle is canted, point of impact can shift rather dramatically. For a southpaw who is willing to adapt his/her shooting style, it may be better, in the long run, to learn to shoot right-handed if his/her right eye is the only good eye. Likewise, if a right-handed shooter can only see well through his left eye, he may benefit from learning how to hold the stock and work the trigger with his left hand. The shooter could still work the bolt with his non-trigger hand. Changing from right-hand to left-hand shooting (or vice-versa) may require a stock swap if the stock is not ambidextrous.

Permalink Gunsmithing 2 Comments »