I've seen a few people reference the report but I have never seen it in full and do not know who performed the test. I know the test compared chrome lined to Melonite but not sure if it also included CHF. Using possible search terms has not produced anything so the title could be something odd or my search engines are wacked.
ETA Yes I know there are a thousand threads about it but I would like to read the real test report, you know how things get twisted on forums.
This one not good enough-
A. L. Foltz and V. Escalone,
February 2011
The current barrel for the M16/M4 is made from chromium-molybdenum-vanadium alloy, with button rifling, and chromium plated bore and chamber. In an effort to increase barrel life to +15,000 rounds various materials and manufacture methods were investigated. A foreign manufacture claimed good results with "GKH" steel and cold rotary forging. A test was run to evaluate the merits of the material and manufacture method.
Sixteen M4 carbines were tested with the following barrels:
A1-A4 - Standard M4 carbine barrel
B1-B4 - GKH material, rotary forged
C1-C4 - Standard material, rotary forged
D1-D4 - GKH material, button rifled
Dispersion data was collected at 1,200 round intervals with one 10 round target at 100 yards, preceded by 3 warmer rounds, velocity data was collected at the same time. Bore erosion was monitored during the 1,200 disassembly/inspection/cleaning. Barrels were considered failed if two of the three circumstances were met: (1) velocity dropped below 200 fps from initial, (2) extreme spread of the 10 round group exceeded 7 inches, or (3) the barrel failed throat erosion.
Results:
Velocity - No barrel dropped below the 200 fps limit during the test.
Erosion measurements (average) - D series passed zero at approximately 7,500 rounds, A at apprx 9,000, C at 9,900, and B at 12,000.
Dispersion (average) - B series dispersion exceeded 7 inches at approximately 1,200 rounds, followed by C at 1,500, A and D at 3,600. However after a total of 13,200 rounds the 10 rounds groups were: A - 32", B - 17", C - 22". and D - 17.5"
One barrel was destructively inspected for chromium coating adhesion, cracking, and wear and heating effects. There appeared to be no difference in heating effects, chromium adhesion or cracking properties between the different material or manufacture methods. There was a difference in wear mechanism. The button rifled barrels showed shear cracking at land root, leading to loss of material, the cold forged barrels exhibited wear on the leading edge of the land with gradual shallowing of the land.
Conclusions:
None of the barrels reach the desired 12,000 life. It is "known" that rotary forged barrels provide a longer life, however in this study, the rotary forged barrels failed dispersion prior to the button rifled barrels.
Recommendations:
Further study is warranted.
ETA Yes I know there are a thousand threads about it but I would like to read the real test report, you know how things get twisted on forums.
This one not good enough-
A. L. Foltz and V. Escalone,
February 2011
The current barrel for the M16/M4 is made from chromium-molybdenum-vanadium alloy, with button rifling, and chromium plated bore and chamber. In an effort to increase barrel life to +15,000 rounds various materials and manufacture methods were investigated. A foreign manufacture claimed good results with "GKH" steel and cold rotary forging. A test was run to evaluate the merits of the material and manufacture method.
Sixteen M4 carbines were tested with the following barrels:
A1-A4 - Standard M4 carbine barrel
B1-B4 - GKH material, rotary forged
C1-C4 - Standard material, rotary forged
D1-D4 - GKH material, button rifled
Dispersion data was collected at 1,200 round intervals with one 10 round target at 100 yards, preceded by 3 warmer rounds, velocity data was collected at the same time. Bore erosion was monitored during the 1,200 disassembly/inspection/cleaning. Barrels were considered failed if two of the three circumstances were met: (1) velocity dropped below 200 fps from initial, (2) extreme spread of the 10 round group exceeded 7 inches, or (3) the barrel failed throat erosion.
Results:
Velocity - No barrel dropped below the 200 fps limit during the test.
Erosion measurements (average) - D series passed zero at approximately 7,500 rounds, A at apprx 9,000, C at 9,900, and B at 12,000.
Dispersion (average) - B series dispersion exceeded 7 inches at approximately 1,200 rounds, followed by C at 1,500, A and D at 3,600. However after a total of 13,200 rounds the 10 rounds groups were: A - 32", B - 17", C - 22". and D - 17.5"
One barrel was destructively inspected for chromium coating adhesion, cracking, and wear and heating effects. There appeared to be no difference in heating effects, chromium adhesion or cracking properties between the different material or manufacture methods. There was a difference in wear mechanism. The button rifled barrels showed shear cracking at land root, leading to loss of material, the cold forged barrels exhibited wear on the leading edge of the land with gradual shallowing of the land.
Conclusions:
None of the barrels reach the desired 12,000 life. It is "known" that rotary forged barrels provide a longer life, however in this study, the rotary forged barrels failed dispersion prior to the button rifled barrels.
Recommendations:
Further study is warranted.
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