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BigLarge
07-21-12, 21:31
Does anyone have muzzle velocity data of a 12.5 compared to an 11.5 (obviously using same ammo)? I've spent some time researching this and cannot find any hard specs.


Thanks in advance.
BC98
07-22-12, 00:13
I don't have comparative data with the 11.5" but I do have some 12.5" numbers.

Do you have a specific load that you were curious about?
BigLarge
07-22-12, 03:15
No particular load in mind! Perhaps well know 556 or 223 in 55g, that would be pretty easy to find comparative data.

Thanks!
BC98
07-22-12, 07:15
XM193: 2900
AE 55gr: 2800
AE 62gr: 2625
GM223M 69gr smk: 2400
GM223M3 77gr smk: 2300
Mk 262 clone: 2500

Barrel was a 12.5" Centurion Arms.
BigLarge
07-23-12, 05:41
XM193: 2900
AE 55gr: 2800
AE 62gr: 2625
GM223M 69gr smk: 2400
GM223M3 77gr smk: 2300
Mk 262 clone: 2500

Barrel was a 12.5" Centurion Arms.

That gives me some good information, thanks.

It appears a 12.5 vs 11.5 only gives you an extra 7-8 feet in frag range using XM193..........
BC98
07-23-12, 09:10
The thing that I had found interesting with this data is that I only lost between 30 to 40fps per inch of barrel with the loads that I have tested. I had always assumed AT LEAST 50 fps/inch.
BigLarge
07-25-12, 19:48
The thing that I had found interesting with this data is that I only lost between 30 to 40fps per inch of barrel with the loads that I have tested. I had always assumed AT LEAST 50 fps/inch.

Right, i had already assumed around 100 FPS/inch (just going on the loss from 16" - 14.5").

Makes me think that, for a non-suppressed weapon, running a 12.5" is not worth it for an urban patrol rifle over the manuverability of an 11.5
the_1iviper
07-26-12, 06:49
with the short barrel check out the black hills 50gr tsx load. with expanding tip bullets you should be good out to 200 to 300 yards and still have the velocity for reliable expansion out of a short barrel. plus you'll get better blind barrier penetration than with m193 or m855.
WS6
07-26-12, 09:07
with the short barrel check out the black hills 50gr tsx load. with expanding tip bullets you should be good out to 200 to 300 yards and still have the velocity for reliable expansion out of a short barrel. plus you'll get better blind barrier penetration than with m193 or m855.

70GR TSX will do better than the 50gr load from a short barrel if you are shooting at distance, unless you are worried about petals shearing up close, which from that short of a barrel is much less likely. The 50gr load really is only good for up-close from long barrels against barriers IMO.
g5m
07-26-12, 11:43
And you'll want to read this thread:
https://www.m4carbine.net/showthread.php?t=105639