M6A2S (Stretch) 14.7" BARREL AMMO VELOCITY TEST

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M6A2S (Stretch) 14.7" BARREL AMMO VELOCITY TEST

Postby JimIslander » Mon Oct 08, 2012 7:00 pm

Folks are always asking about velocity versus barrel length, so I thought I would run a few tests today. Ran seven different off-the-shelf ammo loads through my M6A2S (stretch). Not surprisingly, both Tula rounds had the lowest and least consistent velocities vs. bullet weight. Shot some Tula full auto last year, and the cycle rate was predictably low.

What was surprising was how consistent the cheap WPA was in velocity. I didn't check how well it groups compared to the others, but velocities were VERY consistent. And it was the least expensive ammo of the bunch. American Eagle 55 grain was the most consistent, but it was also the only FMJ 55 Gn. I tested.

As usual, no failures of any kind.

RIFLE: M6A2S, MRE
BARREL LENGTH: 14.7"
TEMPERATURE: 65 Degrees F
CHRONOGRAPH: Competition Electronics ProChrono Digital
DISTANCE TO CHRONOGRAPH FROM MUZZLE: 15 feet

Image

NOTE ON Competition Electronics ProChrono Digital:
Instead of using the v-bars and light shields on this chronograph, I just put translucent packing tape over the sensors. This acts as a diffuser and enables measurements under a very wide variety of lighthing conditions. Can measure anything, even BBs, which are notoriously hard to register on a chronograph.
Last edited by JimIslander on Mon Oct 08, 2012 10:49 pm, edited 1 time in total.
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Re: M6A2S (Stretch) 14.7" BARREL AMMO VELOCITY TEST

Postby TH317 » Mon Oct 08, 2012 7:20 pm

By "packaging tape" are you referring to the 2" wide translucent light brown variety, or just the clear type? I have a buddy who is always complaining about his chronograph not picking up his shots.
Troy

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"Bad men need nothing more to compass their ends, than that good men should look on and do nothing." - John Stuart Mill
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Re: M6A2S (Stretch) 14.7" BARREL AMMO VELOCITY TEST

Postby JimIslander » Mon Oct 08, 2012 8:28 pm

Clear tape. I've tested it in the shade of trees and under pure bright sunlight by the pool. Amazing how well it works and under so many conditions. Not my idea. Found it on the internet. :mrgreen:
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Re: M6A2S (Stretch) 14.7" BARREL AMMO VELOCITY TEST

Postby TH317 » Mon Oct 08, 2012 8:41 pm

Thanks! I'll pass that on. My buddy always told me he got the most consistent results when shooting on a cloudy day. This should give him some options.
Troy

"I'd rather be judged by 12 than carried by 6." - Col. Jeff Cooper

"Bad men need nothing more to compass their ends, than that good men should look on and do nothing." - John Stuart Mill
TH317
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Re: M6A2S (Stretch) 14.7" BARREL AMMO VELOCITY TEST

Postby JimIslander » Mon Oct 08, 2012 8:54 pm

TH317 wrote:Thanks! I'll pass that on. My buddy always told me he got the most consistent results when shooting on a cloudy day. This should give him some options.


I shoot about 6" above the chrono, dead centered as possible, at about 15 feet away. I take my time to precisely line it up with the bullet path.
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