Molon
10-21-15, 17:49
Barnes Precision Match: 5.56x45mm 85 Grain OTM BT
https://app.box.com/shared/static/hqj4xfzx0tdb7ln8gbqhlnk3obi5hhyl.jpg
While most well known as a manufacturer of monolithic copper bullets, Barnes is now producing lead-core, copper-jacketed bullets and loading their own ammunition with these bullets to boot. The focus of this article is one of the loads from the Barnes Precision Match line-up that utilizes one of their lead-core copper-jacketed bullets. As the name for this line of ammunition implies, Barnes stated that the “main focus for this product is accuracy.”
As the title of this article states, the ammunition reviewed for this article is a 5.56mm load (not a 223 Remington load) and there is a warning on the box label stating this ammunition is “NOT FOR USE” in 223 Remington chambers.
This load uses the same 85 grain OTM bullet that Barnes sells as the 85 grain “Match Burner” reloading component, with one exception; the projectile in the loaded ammunition has a cannelure. Barnes stated that they manufacture the bullet for the loaded ammunition with a cannelure “because it will most likely be fired from an AR style platform.” Naturally, I’ll be evaluating the accuracy/precision of this loaded ammunition using an AR-15. The 85 grain Match Burner has an advertised ballistic coefficient of .410.
https://app.box.com/shared/static/bvu0dexs4thhc829prfa6s6jodfery5d.jpg
https://app.box.com/shared/static/smyr8cunc2pbe4s86dckg1m0y4a8d2ji.jpg
The 85 grain Match Burner bullet is one of the longest projectiles that is currently being commercially loaded to magazine length in 5.56mm ammunition. The bullet has a nominal length of 1.069” and Barnes recommends that this bullet be used with a barrel that has a 1:8” twist rate, or faster. This Barnes Precision Match ammunition has a loaded cartridge nominal OAL of 2.245”.
https://app.box.com/shared/static/wktkw3cndntfwectgja2zygiai9vyj91.jpg
The Barnes Precision Match ammunition is charged with a temperature stable ball powder. The round is assembled in a brass case with a headstamp that reads “BBR 5.56 13”. The “BBR” on the headstamp stands for “Barnes Ballistics Research.” Barnes stated that they “source the brass from a European manufacturer.” The primer pocket is sealed and has three “stab” crimps. There is a slight taper crimp at the case-mouth, but no case-mouth sealant.
https://app.box.com/shared/static/beq1f6g6ph4xd03cdup3nr03i9c0a59w.jpg
The individual squares in the red grid shown below are 1/10th of an inch.
https://app.box.com/shared/static/54ti5hzoonphssa6bpe2tcrry4h1pm8x.jpg
I chronographed the Barnes Precision Match 5.56mm 85 grain OTM ammunition from a semi-automatic AR-15 with a chrome-lined, NATO chambered 20” Colt M16A2 barrel with a 1:7” twist.
https://app.box.com/shared/static/374vf9qhvsohvszasr6r7qef15pkrlxd.jpg
Chronographing was conducted using an Oehler 35-P chronograph with “proof screen” technology. The Oehler 35P chronograph is actually two chronographs in one package that takes two separate chronograph readings for each shot and then has its onboard computer analyze the data to determine if there is any statistically significant difference between the two readings. If there is a statistically significant difference in the readings, the chronograph “flags” the shot to let you know that the data is invalid. There was no invalid data flagged during this testing.
The velocity stated below is the muzzle velocity as calculated from the instrumental velocity using Oehler’s Ballistic Explorer software program. The string of fire consisted of 10 rounds over the chronograph.
https://app.box.com/shared/static/qecrizgcgxyzqztvq5xvb9gczasq71q3.jpg
https://app.box.com/shared/static/psjsdukng1c4p5efyw096kuka7p2aliu.jpg
Each round was single-loaded and cycled into the chamber from a magazine fitted with a single-load follower. The bolt locked-back after each shot allowing the chamber to cool in between each shot. This technique was used to mitigate the possible influence of “chamber-soak” on velocity data. Each new shot was fired in a consistent manner after hitting the bolt release. Atmospheric conditions were monitored and recorded using a Kestrel 4000 Pocket Weather Tracker.
https://app.box.com/shared/static/rwruh372al3yh9kafscx370ewe74e6el.jpg
Atmospheric conditions
Temperature: 73 degrees F
Humidity: 44%
Barometric pressure: 29.64 inches of Hg
Elevation: 950 feet above sea level
The muzzle velocity for the 10-shot string of the Barnes Precision Match 5.56mm 85 grain OTM ammunition fired from the 20” Colt barrel was 2583 FPS with a standard deviation of 10 FPS and a coefficient of variation of 0.39%.
For those of you who might not be familiar with the coefficient of variation (CV), it is the standard deviation, divided by the mean (average) muzzle velocity and then multiplied by 100 and expressed as a percentage. It allows for the comparison of the uniformity of velocity between loads in different velocity spectrums; e.g. 77 grain loads running around 2,650 fps compared to 55 grain loads running around 3,250 fps.
For comparison, the mil-spec for M193 allows for a coefficient of variation of approximately 1.2%, while one of my best 77 grain OTM hand-loads, with a muzzle velocity of 2639 PFS and a standard deviation of 4 FPS, has a coefficient of variation of 0.15%.
https://app.box.com/shared/static/lz3su91r4ps75es4s3q97vpm1pdlri73.jpg
…..
I conducted an accuracy (technically, precision) evaluation of the Barnes Precision Match 5.56mm 85 grain OTM ammunition following my usual protocol. This accuracy evaluation used statistically significant shot-group sizes and every single shot in a fired group was included in the measurements. There was absolutely no use of any group-reduction techniques (e.g. fliers, target movement, Butterfly Shots).
The shooting set-up will be described in detail below. As many of the significant variables as was practicable were controlled for. Also, a control group was fired from the test-rifle used in the evaluation using match-grade, hand-loaded ammunition; in order to demonstrate the capability of the barrel. Pictures of shot-groups are posted for documentation.
All shooting was conducted from a concrete bench-rest from a distance of 100 yards (confirmed with a laser rangefinder.) The barrel used in the evaluation was free-floated. The free-float handguards of the rifle rested in a Sinclair Windage Benchrest, while the stock of the rifle rested in a Protektor bunny-ear 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 shield was attached to the objective-bell of the scope. Wind conditions on the shooting range were continuously monitored using a Wind Probe. The set-up was very similar to that pictured below.
https://app.box.com/shared/static/8ybmvvks8dyx1t1soslfzpxgah071370.jpg
The Wind Probe.
https://app.box.com/shared/static/h3eyer905xoqn6e6j0ycsmwde642x00m.jpg
The test vehicle for this evaluation was one of my semi-automatic precision AR-15s with a 20” stainless-steel Lothar Walther barrel. The barrel has a 223 Wylde chamber with a 1:8” twist. Prior to firing the Barnes 5.56mm 85 grain OTM ammunition, I fired a 10-shot control group using match-grade hand-loads topped with the Sierra 77 grain Tipped MatchKing. That group had an extreme spread of 0.68”.
https://app.box.com/shared/static/xac10i5ekkey7ih9ej5a3n6nmv5gy4j9.jpg
https://app.box.com/shared/static/1qk5zsmqf54d5ohcue1ejn6jxo40izn9.jpg
Next, three 10-shot groups of the Barnes Precision Match 5.56mm 85 grain OTM were fired in a row with the resulting extreme spreads:
0.81”
0.76”
0.87”
for a 10-shot group average extreme spread of 0.81”. 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 30-shot composite group was 0.22”.
The smallest 10-shot group . . .
https://app.box.com/shared/static/62neyqaec8aoha2u0ia2s0hoyw14mezv.jpg
The 30-shot composite group . . .
https://app.box.com/shared/static/dlqx21swkqs0myqucyhvqzzwqkny6rpu.jpg
….
https://app.box.com/shared/static/hqj4xfzx0tdb7ln8gbqhlnk3obi5hhyl.jpg
While most well known as a manufacturer of monolithic copper bullets, Barnes is now producing lead-core, copper-jacketed bullets and loading their own ammunition with these bullets to boot. The focus of this article is one of the loads from the Barnes Precision Match line-up that utilizes one of their lead-core copper-jacketed bullets. As the name for this line of ammunition implies, Barnes stated that the “main focus for this product is accuracy.”
As the title of this article states, the ammunition reviewed for this article is a 5.56mm load (not a 223 Remington load) and there is a warning on the box label stating this ammunition is “NOT FOR USE” in 223 Remington chambers.
This load uses the same 85 grain OTM bullet that Barnes sells as the 85 grain “Match Burner” reloading component, with one exception; the projectile in the loaded ammunition has a cannelure. Barnes stated that they manufacture the bullet for the loaded ammunition with a cannelure “because it will most likely be fired from an AR style platform.” Naturally, I’ll be evaluating the accuracy/precision of this loaded ammunition using an AR-15. The 85 grain Match Burner has an advertised ballistic coefficient of .410.
https://app.box.com/shared/static/bvu0dexs4thhc829prfa6s6jodfery5d.jpg
https://app.box.com/shared/static/smyr8cunc2pbe4s86dckg1m0y4a8d2ji.jpg
The 85 grain Match Burner bullet is one of the longest projectiles that is currently being commercially loaded to magazine length in 5.56mm ammunition. The bullet has a nominal length of 1.069” and Barnes recommends that this bullet be used with a barrel that has a 1:8” twist rate, or faster. This Barnes Precision Match ammunition has a loaded cartridge nominal OAL of 2.245”.
https://app.box.com/shared/static/wktkw3cndntfwectgja2zygiai9vyj91.jpg
The Barnes Precision Match ammunition is charged with a temperature stable ball powder. The round is assembled in a brass case with a headstamp that reads “BBR 5.56 13”. The “BBR” on the headstamp stands for “Barnes Ballistics Research.” Barnes stated that they “source the brass from a European manufacturer.” The primer pocket is sealed and has three “stab” crimps. There is a slight taper crimp at the case-mouth, but no case-mouth sealant.
https://app.box.com/shared/static/beq1f6g6ph4xd03cdup3nr03i9c0a59w.jpg
The individual squares in the red grid shown below are 1/10th of an inch.
https://app.box.com/shared/static/54ti5hzoonphssa6bpe2tcrry4h1pm8x.jpg
I chronographed the Barnes Precision Match 5.56mm 85 grain OTM ammunition from a semi-automatic AR-15 with a chrome-lined, NATO chambered 20” Colt M16A2 barrel with a 1:7” twist.
https://app.box.com/shared/static/374vf9qhvsohvszasr6r7qef15pkrlxd.jpg
Chronographing was conducted using an Oehler 35-P chronograph with “proof screen” technology. The Oehler 35P chronograph is actually two chronographs in one package that takes two separate chronograph readings for each shot and then has its onboard computer analyze the data to determine if there is any statistically significant difference between the two readings. If there is a statistically significant difference in the readings, the chronograph “flags” the shot to let you know that the data is invalid. There was no invalid data flagged during this testing.
The velocity stated below is the muzzle velocity as calculated from the instrumental velocity using Oehler’s Ballistic Explorer software program. The string of fire consisted of 10 rounds over the chronograph.
https://app.box.com/shared/static/qecrizgcgxyzqztvq5xvb9gczasq71q3.jpg
https://app.box.com/shared/static/psjsdukng1c4p5efyw096kuka7p2aliu.jpg
Each round was single-loaded and cycled into the chamber from a magazine fitted with a single-load follower. The bolt locked-back after each shot allowing the chamber to cool in between each shot. This technique was used to mitigate the possible influence of “chamber-soak” on velocity data. Each new shot was fired in a consistent manner after hitting the bolt release. Atmospheric conditions were monitored and recorded using a Kestrel 4000 Pocket Weather Tracker.
https://app.box.com/shared/static/rwruh372al3yh9kafscx370ewe74e6el.jpg
Atmospheric conditions
Temperature: 73 degrees F
Humidity: 44%
Barometric pressure: 29.64 inches of Hg
Elevation: 950 feet above sea level
The muzzle velocity for the 10-shot string of the Barnes Precision Match 5.56mm 85 grain OTM ammunition fired from the 20” Colt barrel was 2583 FPS with a standard deviation of 10 FPS and a coefficient of variation of 0.39%.
For those of you who might not be familiar with the coefficient of variation (CV), it is the standard deviation, divided by the mean (average) muzzle velocity and then multiplied by 100 and expressed as a percentage. It allows for the comparison of the uniformity of velocity between loads in different velocity spectrums; e.g. 77 grain loads running around 2,650 fps compared to 55 grain loads running around 3,250 fps.
For comparison, the mil-spec for M193 allows for a coefficient of variation of approximately 1.2%, while one of my best 77 grain OTM hand-loads, with a muzzle velocity of 2639 PFS and a standard deviation of 4 FPS, has a coefficient of variation of 0.15%.
https://app.box.com/shared/static/lz3su91r4ps75es4s3q97vpm1pdlri73.jpg
…..
I conducted an accuracy (technically, precision) evaluation of the Barnes Precision Match 5.56mm 85 grain OTM ammunition following my usual protocol. This accuracy evaluation used statistically significant shot-group sizes and every single shot in a fired group was included in the measurements. There was absolutely no use of any group-reduction techniques (e.g. fliers, target movement, Butterfly Shots).
The shooting set-up will be described in detail below. As many of the significant variables as was practicable were controlled for. Also, a control group was fired from the test-rifle used in the evaluation using match-grade, hand-loaded ammunition; in order to demonstrate the capability of the barrel. Pictures of shot-groups are posted for documentation.
All shooting was conducted from a concrete bench-rest from a distance of 100 yards (confirmed with a laser rangefinder.) The barrel used in the evaluation was free-floated. The free-float handguards of the rifle rested in a Sinclair Windage Benchrest, while the stock of the rifle rested in a Protektor bunny-ear 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 shield was attached to the objective-bell of the scope. Wind conditions on the shooting range were continuously monitored using a Wind Probe. The set-up was very similar to that pictured below.
https://app.box.com/shared/static/8ybmvvks8dyx1t1soslfzpxgah071370.jpg
The Wind Probe.
https://app.box.com/shared/static/h3eyer905xoqn6e6j0ycsmwde642x00m.jpg
The test vehicle for this evaluation was one of my semi-automatic precision AR-15s with a 20” stainless-steel Lothar Walther barrel. The barrel has a 223 Wylde chamber with a 1:8” twist. Prior to firing the Barnes 5.56mm 85 grain OTM ammunition, I fired a 10-shot control group using match-grade hand-loads topped with the Sierra 77 grain Tipped MatchKing. That group had an extreme spread of 0.68”.
https://app.box.com/shared/static/xac10i5ekkey7ih9ej5a3n6nmv5gy4j9.jpg
https://app.box.com/shared/static/1qk5zsmqf54d5ohcue1ejn6jxo40izn9.jpg
Next, three 10-shot groups of the Barnes Precision Match 5.56mm 85 grain OTM were fired in a row with the resulting extreme spreads:
0.81”
0.76”
0.87”
for a 10-shot group average extreme spread of 0.81”. 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 30-shot composite group was 0.22”.
The smallest 10-shot group . . .
https://app.box.com/shared/static/62neyqaec8aoha2u0ia2s0hoyw14mezv.jpg
The 30-shot composite group . . .
https://app.box.com/shared/static/dlqx21swkqs0myqucyhvqzzwqkny6rpu.jpg
….