Muzzle Velocity

[mxmaniac2004]

10 shot strings through my 18" Brux barrel gave me

Hornady factory 123 AMAX
2471 fps average
36 fps extreme spread

PPU factory 120 hpbt
2476 fps average
35 fps E.S

[RangerRick]

We've had some discussions about chrono results on here before, and there seems to be quite a variance from chrono to chrono even with the same barrel length.

Some of that could be altitude, temp, humidity, twist rate, rifling, barrel age, etc., but they do tend to vary. Mine reads slow compared to most when measuring the Hornady factory 123 AMax.

But it's a good relative measure. My hand loads with AA2520 and CFE are about 25-30 fps faster than the factory ammo, and just as accurate, or more so.

RR

[LRRPF52]

Yesterday, I chrono'd many loads from two Lilja-barreled 6.5 Grendel's.

17.6" Lilja barrel:
123gr Hornady SST factory 30JUN2015
2441
2467
2477
2489
2481

18.5" Lilja barrel:
123gr Hornady SST factory 30JUN2015
2468
2441
2421
2495
2453

16" AA/Shaw barrel:
123gr Lapua Scenar Precision Firearms factory 03APR2012
2447
2451
2454
2450

123gr Hornady A-MAX factory 25MAY2013
2365?
2470
2422
2470
2460

These have all been with a Chrony Beta model, 15ft from the muzzle. The 6.5 Grendel Reloading Handbooks have a ton of data and barrel length estimator graphs.

[keystone183]

17.6" Lilja barrel:
123gr Hornady SST factory 30JUN2015
2441
2467
2477
2489
2481

18.5" Lilja barrel:
123gr Hornady SST factory 30JUN2015
2468
2441
2421
2495
2453

This correct, or backwards? And if correct, care to elaborate?

[LRRPF52]

It's correct. Not much to elaborate on really. Different barrels have different personalities. My 16" averages faster than the 17.6" and 18.5" Lilja's. Could be the tighter twist rate, rifling type, or just bore surface. The Lilja's are one of the smoothest, if not the smoothest barrels I have ever seen.

My Lilja's are 1/8 twist. My 16" AA is 1/7.5 or 1/7.75.

[1911man]

So i was finally able to chrony my 18" BHW 1x9 twist barrel. Factory SSTs shot as follows.
1.2490
2.2472
3.2508
4.2480
5.2525
Thats an average of 2485 which is just slightly lower than I expected.
My 120 smk handloads came right in at the same area at 2486 average.

[LRRPF52]

You should be able to get 80-100fps faster than that with CFE and a 123gr AMX or SST, with room in between for at least one accuracy node, if not two.

[1911man]

The problem with that is my rifle seems to hate CFE 223. I worked up 5 loads of 123 AMAX and 5 loads of 120 SMK based on a ladder test and all 5 of each were lousy groups and I had a couple of mis-feeds while I haven't had mis-feeds with any other powder. The best load I found was 31.5 grains and a 123 AMAX but it was noticeably hotter than any other load Ive had, it shot about 1MOA, and I had a stove pipe on the second round. I am about ready to give up on that powder. XBR has done much better for me, but is slower.

[LRRPF52]

What gas port location and dimensions do you have?

[1911man]

I am not sure what you mean by dimensions, but its .730 in front of the gas block, mid length.

[LRRPF52]

Diameter of the gas port hole.

[1911man]

Oh, I am not sure.

[bulletpoints]

Exactly 2,500 fps out of a Shilen 20" heavy barrel. That's with factory Hornady 123 gr. AMAX. I've shot it in competitions from 600 yards to 1,000 yards.