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M1 bullet

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29 September 2008, 05:17
Fat_Albert
M1 bullet
Dose anyone out there know what the BC of the 30cal M1 ball bullet is??
29 September 2008, 08:05
Cheechako
Albert

Interesting question. I've never seen it asked before. I don't know what the number is but maybe someone can calculate it approximately or interpolate it from similar bullets?

174.5 grains
9 degree boat tail
Boat tail length .260"
Boat tail diameter .240"
7 ogive
Nose length .740"
1.304" length
.300" approx bearing surface
Cannelured

Ray


Arizona Mountains
29 September 2008, 21:54
Larry Gibson
Actual measured BC using a M43 Oehler PBL of M1 (M72/M118) bullet at 2600 fps is .524 based on a G1 function (same G function as most bullet makers use). That figure changes a bit day to day as the conditions change. It also drops a bit with velocity over 2700 fps. The average BC will change slightly given 2 different test strings of the same ammo just as average fps will vary slightly. The variation amounts to about as much difference if asking yourself; is that deer at 386 yards or 387 yards?

That BC of .524 is the one I use for my ballistic calculation for my '06 load with that bullet. It works fine to 1400 yards when shot out of my M1903 at 2640 fps.

Larry Gibson
29 September 2008, 22:24
Cheechako
Larry

Great info. Question - does the cannelure have any effect on BC? Don't most of the Match loads (M72/M118) use the bullet without a cannelure?

Ray


Arizona Mountains
02 October 2008, 05:59
Fat_Albert
Great Thanks for the info DO you have the BC on the M2 ball bullet? Cool