September 13th, 2017

How Velocity Changes with Barrel Length — .223 Rem Test Results

.223 Rem Cut-Down Test barrel UMC m855

Most of us own a .223 Rem rifle. Now, thanks to our friends at Rifleshooter.com we can assess exactly how velocity changes with barrel length for this popular cartridge.

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.

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, Reloading 3 Comments »
May 20th, 2017

How to Prematurely Kill a Barrel — .243 Win Fast Firing Test

barrel life test rapid fire cooling

Can sustained rapid-fire shooting with no cool-down period wear out a quality barrel more quickly? The answer is “Yes” according to Forum member LCazador, who did an interesting comparison test with two .243 Winchester barrels. He started off with two, identical, match-grade HV taper stainless barrels. Both were NEW at the start of testing, and LCazador shot the same load through each: 95gr match bullets with 38 grains of Hodgdon Varget. After giving both barrels the same, gentle 20-round break-in, 300 rounds were then fired through each barrel — in very different ways. Barrel condition and wear were monitored with a borescope.

Barrel One — Slow Fire, Cool Down Periods, Cleaning Every 50 Rounds
At the end of the 300-round test, Barrel One looked brand new. There was none of the severe fire cracking found in Barrel Two. This barrel was shot no more than 10 times without a cool down and firing was done at a much slower pace. Cleaning for this barrel was done every 50 shots.

Barrel Two — Fast Firing, No Waiting, Cleaning Every 100 Rounds
The second barrel, which received hard use and minimal cleaning, was severely damaged with severe fire cracking at the leade and throat. As a result, the barrel had to be re-chambered. This barrel was shot 100 rounds at time without cleaning and was shot up to 20 times in succession without a cool down.

LESSON LEARNED — Heat Kills Barrel Life
Don’t let your barrel get too hot, and keep it clean. One afternoon can ruin a barrel!

Hawkeye Borescope imageMonitoring Barrel Wear with Borescope
Some folks worry too much about what their borescopes reveal — many barrels do not have to be “squeaky clean” to perform well. In fact some barrels run better after ten or more fouling shots. However, a borescope can be very helpful when your barrel starts losing accuracy for no apparent reason. Forum member FdShuster writes:

“A borescope is a positive way of backing up your suspicions when the rifle starts to throw an occasional (soon followed by more frequent) wild shot. Using the scope is also an excellent way to determine that the cause is barrel wear and not simply a need for a concentrated cleaning session to remove built up copper and more importantly, carbon fouling.

I’ve had a few barrels that gave every indication of being shot out. But I ‘scoped them out and found the cause to be nothing more than requiring a good cleaning. They then returned to their usual performance. There’s no guessing involved when you are able to get ‘up close and personal’ using the scope. The borescope also provides an excellent view of the all-important condition of the crown. My borescope is one of the most valuable investments I’ve ever made.”

Permalink Gunsmithing, Tech Tip 2 Comments »
May 29th, 2016

Barrel Length and Velocity in a .223 Rem — Barrel Cut-Down Test

.223 Rem Cut-Down Test barrel UMC m855

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.

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 4 Comments »