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Deceased May 2nd, 2020
Last edited by Cosine26; 05-15-2010 at 01:10 AM.
Reason: omitted word
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Thank You to Cosine26 For This Useful Post:
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05-15-2010 01:06 AM
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Very Interesting! Thanks for digging this up.
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Deceased May 2nd, 2020
AP vs Ball Part 2
AP vs Ball Part 2
In 1943 when it became obvious to the Ordnance department that 30M2AP was being used extensively by the ground forces (particularly in Europe where there was a lot of metal on the battle field) in lieu of Ball ,a series of tests were conducted to evaluate the difference between 30M2 Ball vs 30M2AP. The results of these Ordnance departments tests were cited in an article “AP vs Ball” by Edwards Brown Jr. in the May 1947 AMERICAN RIFLEMAN.
The information for the M1919A4 MG is sparse ( It was reported atat a 2.5% increase was noted when using AP vs ball) but the report on the two rifles is fairly detailed. As previously reported, four rifles were selected for the test: two M1’s with four groove barrels and two 03A3’s with two-groove barrels. Two lots of ammo were selected for the entire test, one lot of AP and another Lot of Ball. The rifles were each fired 6000 rounds at a rate of fire of ~ 40 rounds per minute with the barrels being water cooled every eighty rounds.
Definitions:
AP = 30M2AP armor piercing ammo
B = 30M2 Ball, ball ammo
IV = Initial velocity at the beginning of the test
EV = End velocity at the end of the test
MR = Mean radius, army ordnance method of specifying accuracy
ExSp =extreme spread in inches
“I” proceeding indicates “initial”- “E” preceding indicates “ending”
Each rifle was fired at the beginning and ending of the tests for three 10-shot groups at 600 yards and the MR, velocity at 78 feet, and Extreme Spread measured.
*FOR THE M1 (4-groove BBL):
Muzzle velocity measurement:
Ball- IV 2699 fps- EV- 2661 fps- change = 38 fps
AP – IV 2694 fps- EV 2616- change = 78 fps
Accuracy Measurement:
Mean Radius:
Ball- I MR 9.7” – E MR 15.4” – Change 37%
AP- I MR 9.3” – E MR 12.0” – change = 22.5%
Extreme Spread
Ball – I ExSp 29.1” – E ExSp 46.9” Change = 38.0 %
AP- I ExSp 11.7” – E ExSp 15.7” –change = 27.0 %
*FOR the 03A3 RIFLE (2-groove BBL):
Ball-IV 2720 fps- EV 2655 fps _ change = 65 fps
AP – IV 2644 fps – EV 2483 fps – change = 161 fps
Accuracy Measurement:
Mean Radius
Ball – I MR - 8.1” – E MR – 10.2” –change = 20 %
AP- I MR 7.6” – E MR 10.7” –change = 29.0%
Extreme Spread
B – I ExSp 21.3” – E ExSp 32.5” – change = 25.2%
AP – I ExSp 23.i” – E ExSp 37.3” – change = 38 %
War time specification for the acceptance of ammunition was:
Ball MR = 7.5”
AP = 10.00 “
Despite the wide specification for AP ,the USMC when it resumed Intra Service competitions in 1946 found that while Ball was slightly more accurate up to 500 yard, beyond 500 yards AP was significantly more accurate. In 1944 the Ordnance department compiled the MR for the first and last lots of ammunition produced at the Denver Ordnance plant that year as follows:
30M2AP
Lot DEN 34470 and Lot 34570
Average MR = 5.05”
30M2 Ball
Lot DEN 15650 and Lot 15750
Average MR = 5.72 “
There is no real correlation between group size and MR but a ‘rule of thumb’ says that group size is ~ 3 times MR.
It has been a long time since I have fired any significant number of AP rounds but it used to be standard practice by the armorers I knew to fire three clips of AP through any re-barreled M1 to “smooth out the bore”. Remember when I was firing AP, barrels could be had through the DCM for: the 03 and the 03A4 for $5.30 and M1 barrels for &8.30.
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Advisory Panel
I don't think you need all those figure to discuss barrel wear, I don't think YOU are going to notice any appreciable wear in your barrel from AP ammo. After all there's a brass jacket to cushion, not tungsten against steel. You're not going to fire exclusively AP anyway are you?
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Legacy Member
A good friend, now passed on, shot in the 1950's. He told me they used 03-A3's and were issued AP ammo, and it was free. He stated a 2 groove barrel would last 18 months. When Garands became available the problem disappeared as the 4 groove barrel was different. These were his remarks, not mine.
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