I have an 18 inch AR that is finicky. Certain good quality hunting ammo, it shots sub moa. Bulk 5.56 and it becomes a 2-3 MOA. Is that common in your experience?

In my opinion, yes 2-3 MOA with bulk is acceptable. I really don't shoot bulk ammo for accuracy often - usually save that for the 3-50 yard drills and ringing steel out to a couple hundred yards.

Bulk 5.56mm isn't meant to be precision stuff.
"Minute of man" at 200-300 meters is pretty much what you'll get from it.

Yep, 2-3 MOA.

quote:

Originally posted by sasquatch28:
I have an 18 inch AR that is finicky. Certain good quality hunting ammo, it shots sub moa. Bulk 5.56 and it becomes a 2-3 MOA. Is that common in your experience?

Your AR isn't finicky.

2-3 MOA is all you are going to get with bulk ammo.

In fact, 2-3 MOA with bulk ammo is pretty good.

Many rifles will do worse than that.

Sounds about right to me. The groups I get out of mine with Hornady TAP FPD are much tighter than anything we would consider "bulk" ammo. Just how it goes.

quote:

Originally posted by sasquatch28:
Is that common in your experience?

Yes.

Being that the military requirement of accuracy is 2MOA, I’d say your rifle is w/I specs with that ammo.

IMO finicky is when a barrel shoots only a few types of quality ammo well. As in sub-MOA potential for most types of match grade ammo, then 2+ MOA for a similar load.

Factory FMJ ammo just don't seem to fly accurately. Maybe some people have handloads of 55 FMJ that are accurate, but I doubt it. You might find a barrel and FMJ load that shoots a little better than 2 MOA -- at least every now and then. Not consistently, however. To top it off, you may obtain 2 MOA at 100 yards, but this might increase to 2.5 MOA at 200 yards and 3 MOA at 300 yards.

Winter weather has slowed my analysis of switching between FMJ ammo and quality loads. Two of my ARs show that 55 FMJ from American Eagle makes subsequent ammo shoot wonky for 10 to 15 rounds.

What kind of AR is it? What's the twist rate on the barrel?

Most 5.56 bulk ammo is 55gr. I see better accuracy with the 1/8 twist using 55gr than with the 1/7 in gereral in run of the mill ARs.

quote:

Originally posted by Blackwater:
I see better accuracy with the 1/8 twist using 55gr than with the 1/7 in gereral in run of the mill ARs.

In one of his ballistics books Bryan Litz discusses why a barrel with a rifling twist rate that’s faster than necessary to stabilize a bullet may be less precise than one that’s not, but another variable is the quality of the barrel itself. A 1/8" rate is rather unusual, I believe, so are we sure that the ones you’ve used weren’t just better than the average 1/7"?

quote:

Originally posted by sigfreund:
In one of his ballistics books Bryan Litz discusses why a barrel with a rifling twist rate that’s faster than necessary to stabilize a bullet may be less precise than one that’s not, but another variable is the quality of the barrel itself. A 1/8" rate is rather unusual, I believe, so are we sure that the ones you’ve used weren’t just better than the average 1/7"?

1:8 twist is pretty common with stainless steel barrels -- I have three in use on my AR-15s and one in a bolt action. Plus two more replacement 1:8 barrels in the wings. I had a 1:7 twist stainless barrel that was very accurate -- on par with my 1:8. My most accurate barrel is a 1:7.7 stainless, with another 7.7 twist stainless pretty close in accuracy.

The 7.7 twists are cut rifled. All my other stainless barrels are button rifled -- 1:9, 1:8, and 1:7 twists.

My least accurate barrel is 1:7 twist -- chromoly, hammer forged, and piston. This barrel shoots 55 FMJ the worst of any of my barrels. It likes 69 SMK loads and nothing else.

However, none of my stainless barrels shot 55 FMJ worth a darn -- twist made no difference.

55 bulk ammo sucks for accuracy. Sure, a good stainless match barrel will help, but 55 FMJ is a great way to degrade an AR15's accuracy to that of a Mini-14.

Quality loads are always a factor.
It's not the only one but a significant one.
It is the main reason I hand load.
YMMV

quote:

Originally posted by sigfreund:

quote:

Originally posted by Blackwater:
I see better accuracy with the 1/8 twist using 55gr than with the 1/7 in gereral in run of the mill ARs.

In one of his ballistics books Bryan Litz discusses why a barrel with a rifling twist rate that’s faster than necessary to stabilize a bullet may be less precise than one that’s not, but another variable is the quality of the barrel itself. A 1/8" rate is rather unusual, I believe, so are we sure that the ones you’ve used weren’t just better than the average 1/7"?

The rifles in question are a Springfield AR 1/8 twist (nothing really special/melonite lined bore- m4 profile), Colt 6920 1/7 and DDM4v7 1/7 (both chrome moly bores/barrels). The DD had the Govt profile/heavier barrel and shot 69gr bullets really well. All 16" barrels.

It's rather anecdotal as I don't have any measured groups from the 3 rifles with a decent scope, except for the DD, which also had a free floating barrel.

The DD in a hand loaded 69gr Sierra Matchking bullet over 22.5gr of H322 would easily do <=.75" 5 shot groups at 100 yards. It really liked that 69gr bullet.

I prefer the versatility of the 1/8 twist to get decent accuracy with 55 or lighter bullets and one of the reasons the Springer is my rifle of choice now.
I'd like to try a S&W MP15T with the same twist rate and the 5r rifling.

I think the issue is with FMJ in general. It's known that hollowpoint bullets are more accurate, everything else being more or less equal. I've heard various theories why that is: shifting back the center-of-gravity, lends itself to more precise manufacturing.

Anyways, I always try to find Federal American Eagle in 50-grain JHP (a non-expanding hollowpoint). It is twice as accurate as their more common 55-grain FMJ, but not that much more in cost.

This message has been edited. Last edited by: kkina,

quote:

Originally posted by Blackwater:
The rifles in question are a Springfield AR 1/8 twist (nothing really special/melonite lined bore- m4 profile), Colt 6920 1/7 and DDM4v7 1/7 (both chrome moly bores/barrels). The DD had the Govt profile/heavier barrel and shot 69gr bullets really well. All 16" barrels.

It's rather anecdotal as I don't have any measured groups from the 3 rifles with a decent scope, except for the DD, which also had a free floating barrel.

I prefer the versatility of the 1/8 twist to get decent accuracy with 55 or lighter bullets and one of the reasons the Springer is my rifle of choice now.

Your estimated accuracy is little more than gut feel without measured groups, especially measured at target distances beyond 100 yards. Many factors can be in play:
- Free floated barrels will be more accurate than those that are not free floated.
- Chrome lined barrels will almost always be less accurate than barrels that aren't chrome lined.
- Cut rifled and button rifled barrels are generally more accurate than hammer forged barrels.
- How a barrel's chamber is cut has a large effect on its accuracy.

I have shot a number of types of light ammo in my various AR barrels, with twists from 1/9 through 1/7. Quality light-bullet ammo shoots equally well in all my barrels, regardless of twist rate. Light ammo that shoots well includes:
55 Hornady Vmax -- from multiple sources -- Hornady, Black Hills, HSM
50 Hornady Vmax -- from Hornady, Blackhills, and HSM
40 Hornady Vmax
55 Hornady BTHP Black
50 Berger Match Varmint from HSM
52 HPBT from Wilson Combat and Black Hills
53 Hornady Vmax from Federal
55 Sierra Blitzking from Aussie Outback
50 tipped varmint from American Eagle

Light ammo that didn't shoot accurately:
55 FMJ from any brand
55 HPBT from Frontier
45 Fiocchi Sinterfire -- frangible bullet
53 Vmax Hornady Superformance -- in general I find the Superformance ammo line to be inaccurate

Not only common but acceptable and even good. As per FM3-22.9 5.1 the minimum standard for zeroing is six rounds into a 4cm circle at 25 meters. That works out to slightly greater than 6 MOA at 100 yards. In my time in uniform I only saw one rifle that was truly out of spec, so this isn't a difficult standard. Most M16\AR15's will easily group half of this, with some being MOA rifles given bulk ammo they like.

quote:

Originally posted by sasquatch28:
I have an 18 inch AR that is finicky. Certain good quality hunting ammo, it shots sub moa. Bulk 5.56 and it becomes a 2-3 MOA. Is that common in your experience?

That's what I get with any bulk 5.56.

A few years ago I tried a few boxes of Silver Bear 62gn hp's for cheap plinking ammo, it has a non-lacquer coated steel case. I get 1.25-1.5" @100 which is better than the 2-3" I get with most surplus So I'm good with Silver Bear for plinking.

I reload so I don't buy high end ammo, and keep Silver Bear just as a back-up and its lacquer sealed so I usually keep some in an ammo can in the truck.

Thanks all!

Very interesting findings. I’m trying to find some better ammo that are closer to the bulk 55gr price point.