Hi all!

I am curious as to how much faster a longer barreled AR would get those 10mm bullets flying versus say a 5 inch barreled handgun???

I imagine a lot of you 10mm guys reload, and in theory, you could use a slower burning powder and possibly wring more speed out of the round.

Thanks in advance!

probably 200-300 fps

I've run 135 gr Noslers at 1650 fps out of my 10 inch RMWXtreme upper.  Ron said you can run them pretty hot in a di ar upper so I can push them harder if I want to.

And



I used to shoot USPSA matches, so I am used to running the math to calculate power factor.

135gr X 1,650fps = 222.75 power factor

135gr X 1,650fps =  182.25 power factor

I'll shoot some bowling pin matches every now and then.  Winchester White Box .45 ACP 230 grain FMJ usually power factors right around 196 for me out of a 5 inch 1911.  A good center hit with one of those really makes those pins fly off the table.

So a 222 power factor round would really make them zing.  

MiHec is going to be sending me a .40 cal hollow point casting mould soon, so powder coating them and running them through an AR sounds like cheap fun.

Thanks for the replies!

Ballistics by the inch

Thank you!

That was helpful.  I guess the accuracy gains or losses that were the smallest were the ones with fast burning powders???

Been a while since I touched this stuff... but here's a thread with charts of some velocity comparisons of different types of 10mm rifle builds

How do you get two different power factors from the same set of numbers?

Whoops!

Bottom velocity should be 1, 350 fps.

I have an RMW 10" 10mm upper.  I haven't chronod it but after seeing some numbers it makes me wish I'd gone 8".



FWIW, my 6" Glock shoots 180gr XTP Underwood and my handloads at 1420fps.  I'm guessing the 10" barrel will be around 150fps faster.

Not a 10mm AR but a HK clone with a 9" barrel. I also load with VV 3N37 but I've not chronoed it yet. It should produce better numbers in terms of ES based on results in 9mm loadings.

Gun: Coharie MP5 clone
Load: Precision Delta 180 FMJ with 11.2 Blue Dot powder & CCI LP primer
FPS: 1494, 1496, 1473, 1471, 1523, 1539, 1496, 1525, 1473, 1504
averaged 1499 ES = 68 / SD = 23

Gun: Coharie MP5 clone
Load: Precision Delta 165 FMJ with 9.5 Longshot powder & LP primer
FPS: 1522, 1522, 1550, 1548, 1546, 1520, 1536, 1561, 1550, 1522
averaged 1537 ES = 41 / SD = 15