SBR ammo - questions

[Voodoo_Man]

So obviously barrel length and bullet matter.

Went to range w/ my PWS MK107P 7.75" pistol, shot 556 IMI 55gr out of it at 100y:



When I moved to 50y:



Shooting prone, supported on magazine, 4 MOA, Aimpoint H1.

What ammo should I be looking at? I carry winchester 64gr and ss109, which I may get better groups with, but I did not try.

What is a fast-burning factory ammo that performs well out of short barrels? Should I expect better results from 77gr?

edit - twist rate is 1:8, 7.75 barrel

[GeorgeB]

I'd look at getting a longer barrel than 7.75 inches, for a start. LOL. Every operator error is going to be magnified, and speaking of magnification, dropping a Geissele trigger in and using a magnified optic may help a bit too.

[Voodoo_Man]

7.5" barrel.....'nuff said.

Thanks for posting, while your post was most definitely not enough said, I would appreciate some factual information backed up by links to testing and/or personal experience with loads (post specifications please) and how they perform out of what length barrel.

[GeorgeB]

See:

https://www.m4carbine.net/showthread...-best-SBR-ammo

or

https://www.m4carbine.net/archive/in.../t-155318.html

But your barrel is too short, frankly, and that's the main "problem"

https://www.m4carbine.net/archive/in...p/t-54320.html

[Voodoo_Man]

Ive read those threads, none if which apply to the question I am asking.

Lets not think of the barrel length as a problem but merely a formula that requires the right variables in order to function.

[HKGuns]

You're not going to want to hear this either, but a group that large at 100 yards is more than an ammo problem voodoo.

With that said, I would look at I4198 or H322 as a couple of fast burning powders with data readily available in .223 using lighter bullets.

I would start with 322 as it is a ball powder and will ignite better than stick.

[Leaveammoforme]

Your barrel is not too short for punching paper accurately. Barrel length does not equal accuracy. As long as projectile is stabilized and doesn't go through trans-sonic flight it will be predictable. Of course you lose muzzle velocity(barrel length) which will cause more projectile drift from wind/gravity and vertical dispersion from high standard deviations. Like any gun, it will like one ammo more than others.

I have a 7.5inch 1-7 twist with a Pro (no magnifier) sitting on it. I scored 15 out of 20 possible hits @ 200 yards with slight 9 o'olock breeze at a recent local match. Targets were 2 eight inch swingers spaced about 3 foot apart. Stage descripition called for alternating targets every shot with a max time of 90 seconds with only 20 shots allowed to complete stage. I favored left on left target for first shot, Impact. Got excited and yanked a few , but gun can do it.

I'm zero'd at 50, +4'ish at 100 and back on at 200. My accuracy load for this gun is 21.2 grains of R10x pushing a Hornady 55 grain SP w/cannelure with a solid factory crimp in LC brass with plain jane WinSR primer at 2.200 COAL. This is a midrange 223 load. RL10x gives me good SD's in this short barrel. It locks bolt back on empty. Is it blistering fast or does it almost knock the swingers over? No, but it is accurate. I switch to hotter ammo for the dynamic stages.

All this rambling and I'm just trying to say:
It will shoot one ammo better than others
Practice x 99, then repeat.
Be aware of environmental issues that a 3100 FPS projectile would shrug off.

[Onyx Z]

I would start with 322 as it is a ball powder and will ignite better than stick.

H322 is an short-cut extruded (stick) powder, not ball. It does meter very well though, almost like ball powder.

When you say IMI 55gr, do you mean this one?

https://www.wideners.com/itemdetail.cfm?item_id=9017

I wouldn't expect anything spectacular with that ammo. It's good ammo, just not match grade. And barrel length has nothing to do with accuracy, so I would try some match ammo before assuming it's the rifle.

[HKGuns]

H322 is an short-cut extruded (stick) powder, not ball. It does meter very well though, almost like ball powder.

Thanks for the correction. I've never used it and assumed it was similar to 335 which I have used extensively.

[Voodoo_Man]

I know the first thing people go for is the user, not the machine, I can tell you with without hesitation that I have no issues with accurate shooting especially from a prone position without any constraining variables.

I have shot enough to know it is the ammo that is the source of the issue, not the barrel length and not my implementation of the rifle.

I do not reload so I am looking for factory fast-burning loads (like I stated in the OP).

I was shooting the IMI, as I stated, yes it is nothing spectacular, but its not exactly crap either.

Next time I hit the range I'd like to get a bunch of different types of ammo and see what works with the short barrel - hence the thread.