Molon
06-13-10, 21:31
IMI M855 2009: Range Report
Lot #00219/K
http://www.box.net/shared/static/s3294ls7g3.jpg
This M855 load has a heavy collet crimp at the case mouth.
http://www.box.net/shared/static/brobgnxv10.jpg
The bullet has a cannelure and the case mouth is sealed with asphalt sealant.
http://www.box.net/shared/static/9uvkapn5r3.jpg
The bullets loaded in this new lot lack the green painted tip of the older lots.
http://www.box.net/shared/static/5dr2p0vm82.jpg
The primer pockets are sealed and crimped.
http://www.box.net/shared/static/7hu8sm8zvl.jpg
The cartridge is charged with ball powder.
http://www.box.net/shared/static/zfznp74gqk.jpg
An accuracy evaluation of this lot of ammunition was performed following my usual protocol. Shooting was conducted from a concrete bench from a distance of 100 yards (confirmed with a laser range finder.) The test vehicle was a 16” Colt HBAR with chrome-lining, a NATO chamber and a 1:9” twist. This is the barrel found on the Colt 6721 Tactical Carbine. The barrel was free-floated with a LaRue Tactical handguard.
http://www.box.net/shared/static/9jkbf66dd6.jpg
The fore-end of the carbine rested in a Sinclair Windage Benchrest and the butt-stock rode in a Protektor rear-bag. Sighting was accomplished via a Leupold VARI-X III set at 25X magnification and adjusted to be parallax-free at 100 yards. A mirage shade was attached to the objective-bell of the scope. Naturally, the wind conditions were monitored using a Wind Probe. The set-up was very similar to that pictured below.
http://www.box.net/shared/static/xo4duzdgtp.jpg
The Wind Probe.
http://www.box.net/shared/static/lkg47ptc04.jpg
A 10-shot control group was fired using match-grade hand-loads topped with Sierra 55 grain BlitzKings. The extreme spread of that group measured 0.89”.
http://www.box.net/shared/static/10bptgnptv.jpg
http://www.box.net/shared/static/r2cnn37f57.jpg
Three 10-shot groups of the IMI M855 were obtained for analysis. The extreme spreads of those groups measured:
2.72”
2.19”
2.24”
for a 10-shot group average of 2.38”. The three 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for the composite group was 0.76”.
http://www.box.net/shared/static/nx01kxtiql.jpg
IMI M855 lot #00256/A
(circa early-mid 2000s?)
http://www.box.net/shared/static/jsgmqg3y1m.jpg
For comparison, I’m including the results of an accuracy evaluation of a previous lot of IMI M855 (lot #00256/A). Testing of this lot was carried-out in the same manner as described above. The test vehicle for this evaluation was a free-floated 20” Colt HBAR with chrome-lining, a NATO chamber and a 1:7’ twist.
http://www.box.net/shared/static/mb1nbnlbet.jpg
The three 10-shot groups obtained using this lot of M855 had extreme spreads that measured:
2.14”
3.01”
1.71”
for a 10-shot group average of 2.29”. As before, the three 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for this composite group was 0.68”. The 30-shot composite groups from both lots are pictured below for comparison.
http://www.box.net/shared/static/c90xtb58cf.jpg
http://www.box.net/shared/static/hlhzuv8crp.jpg
M855 lot #00256/A was chronographed using an Oehler 35-P with “proof-screen” technology. All strings of fire consisted of 10 shots each. All of the velocities posted below are MUZZLE velocities which were calculated from the instrumental velocities using Oehler’s Ballistic Explorer software. Chronograph data for M855 lot #00219/K will be posted in this thread, hopefully, within the next few weeks.
http://www.box.net/shared/static/gqcniteei4.jpg
http://www.box.net/shared/static/ohi7k3kaid.jpg
.....
Lot #00219/K
http://www.box.net/shared/static/s3294ls7g3.jpg
This M855 load has a heavy collet crimp at the case mouth.
http://www.box.net/shared/static/brobgnxv10.jpg
The bullet has a cannelure and the case mouth is sealed with asphalt sealant.
http://www.box.net/shared/static/9uvkapn5r3.jpg
The bullets loaded in this new lot lack the green painted tip of the older lots.
http://www.box.net/shared/static/5dr2p0vm82.jpg
The primer pockets are sealed and crimped.
http://www.box.net/shared/static/7hu8sm8zvl.jpg
The cartridge is charged with ball powder.
http://www.box.net/shared/static/zfznp74gqk.jpg
An accuracy evaluation of this lot of ammunition was performed following my usual protocol. Shooting was conducted from a concrete bench from a distance of 100 yards (confirmed with a laser range finder.) The test vehicle was a 16” Colt HBAR with chrome-lining, a NATO chamber and a 1:9” twist. This is the barrel found on the Colt 6721 Tactical Carbine. The barrel was free-floated with a LaRue Tactical handguard.
http://www.box.net/shared/static/9jkbf66dd6.jpg
The fore-end of the carbine rested in a Sinclair Windage Benchrest and the butt-stock rode in a Protektor rear-bag. Sighting was accomplished via a Leupold VARI-X III set at 25X magnification and adjusted to be parallax-free at 100 yards. A mirage shade was attached to the objective-bell of the scope. Naturally, the wind conditions were monitored using a Wind Probe. The set-up was very similar to that pictured below.
http://www.box.net/shared/static/xo4duzdgtp.jpg
The Wind Probe.
http://www.box.net/shared/static/lkg47ptc04.jpg
A 10-shot control group was fired using match-grade hand-loads topped with Sierra 55 grain BlitzKings. The extreme spread of that group measured 0.89”.
http://www.box.net/shared/static/10bptgnptv.jpg
http://www.box.net/shared/static/r2cnn37f57.jpg
Three 10-shot groups of the IMI M855 were obtained for analysis. The extreme spreads of those groups measured:
2.72”
2.19”
2.24”
for a 10-shot group average of 2.38”. The three 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for the composite group was 0.76”.
http://www.box.net/shared/static/nx01kxtiql.jpg
IMI M855 lot #00256/A
(circa early-mid 2000s?)
http://www.box.net/shared/static/jsgmqg3y1m.jpg
For comparison, I’m including the results of an accuracy evaluation of a previous lot of IMI M855 (lot #00256/A). Testing of this lot was carried-out in the same manner as described above. The test vehicle for this evaluation was a free-floated 20” Colt HBAR with chrome-lining, a NATO chamber and a 1:7’ twist.
http://www.box.net/shared/static/mb1nbnlbet.jpg
The three 10-shot groups obtained using this lot of M855 had extreme spreads that measured:
2.14”
3.01”
1.71”
for a 10-shot group average of 2.29”. As before, the three 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for this composite group was 0.68”. The 30-shot composite groups from both lots are pictured below for comparison.
http://www.box.net/shared/static/c90xtb58cf.jpg
http://www.box.net/shared/static/hlhzuv8crp.jpg
M855 lot #00256/A was chronographed using an Oehler 35-P with “proof-screen” technology. All strings of fire consisted of 10 shots each. All of the velocities posted below are MUZZLE velocities which were calculated from the instrumental velocities using Oehler’s Ballistic Explorer software. Chronograph data for M855 lot #00219/K will be posted in this thread, hopefully, within the next few weeks.
http://www.box.net/shared/static/gqcniteei4.jpg
http://www.box.net/shared/static/ohi7k3kaid.jpg
.....