Differences in accuracy of ammo

[John C.]

Just wondering.... I own a couple of military style rifles (an AK, an FAL, an AR10 and an AR15). Have always shot predominately mil surp. ammo out of each. On those occasions I've sprung for match ammo (for the AR15) I never noticed a huge difference. My heavy stainless 1 in 9 twist barrel really loved Hornady V-max, but shot a wide variety of 55 and 62 grain bullets equally well - usually around 1.5 moa or better. Just bought my second AR, with a 1 in 8 chrome lined barrel and wow, what a difference. The first time I took it to the range and shot my usual cheap 55 grain loads (two different mfgs), the results sucked. So much so that I thought there was either something wrong with me or the rifle. I was ready to ship my gun back to the mfg.

However, I thought maybe it's the ammo. I also worried that I haven't done a lot of shooting lately and maybe it was me that really sucked.

Went back to the range with a bunch of ammo, and my other AR. Started out with some 77 grain Black Hills match ammo that I found. Figured if the results still sucked it was either me or the gun. The results were pretty good - around 1.25 moa at 100 yards. This was with a 4 x scope and me being less than perfect behind the trigger. i was beginning to think maybe I just had a bad day before.

But then I tried some more 55 grain cheap ammo and the results went back to being terrible. We're talking 4+ inch groups at 100 yards.

Anyone else experienced anything like this? Is it the cheap ammo? The 55 grain vs. 77 grain? I did try the 55 grain Hornady that my other AR loves, and the results were kind of in between the Black Hills and the cheap stuff. Maybe 2 inch groups.

I'm really hoping that it's going to be a bullet weight thing. Or at least that I will be able to find some reasonably priced ammo that this gun likes. I can live with 2 MOA, particularly since I will mostly be shooting at steel plates with a maximum distance of 200 yards. But for 4 MOA is unacceptable from what is a pretty expensive AR. And I really don't want to have to buy $1.00 a round match ammo to feed this thing.

 

[mac1911]

What AR do you have ? Heres my results from my remaining ARs for accuracy. This is all shot from a leadsled rifle rest. I like to take myself out of the equation as much as possible.
1. RRA NM A2 off the rest with hornady match has shot many 1" groups. I have only shot my reloads with 75gn hornady FMJHP these also hover in that 1+" area
2. RRA standard A2 just under keeps under 2 with better than average ammo with no real signs of getting better with high grade ammo. 3-4" with 193 or 855
Steel cased ammo is all over the place both good and bad groups and can differ from box to box in the same lot!
3. Stag model 2 carbine runs around 3.5-4 " groups with just about everything.
I dont think the military puts a huge demand on the "military" ammo. I though I read 4moa was good enough for military specs and their testing is all to do about averages, median and some other stuff that makes it hard to fail the test. ?????
your 1;8 barrel should shoot 55s to 75ish fine?

Now mind you im lucky to hold a sub 4" groups shooting prone with a sling!

 

[John C.]

Wow, I'd kind of given up on anyone responding. Thanks for posting mac1911. To answer you're question, the new AR I've been having issues with is a POF. Interestingly enough, a couple of days after posting this thread, I came across a thread in the general discussion forum by someone who was having similar issues with the POF he had just bought. It was basically the identical gun (down to the same 14.5 inch barrel with muzzle break). We've both been having the same problems. Poor accuracy with cheap 55 grain ammo. (And I'm not even talking about steel cased stuff, but like American Eagle.) We also were getting a pretty significant shift in point of impact between various ammo. In both cases, lighter bullets seemed to shift 2-3 inches to the left.

After I posted in his thread, we PM'd each other, and both wrote to POF. There response to me was that this sounded strange and that they couldn't really diagnose the problem unless I sent the upper back. I still may do this, but want to try going to the range once or twice more first, and play around with different brands of ammo. If I can find some relatively inexpensive ammo (mil surp, priv. part., etc.) that will hold even 2-3 inch groups, I can live with it. The rifle only has a 14.5 inch barrel and a 1 x 4 scope and I use it mostly to shoot paper and steel targets at 0-200 yards, so I don't need bench rest accuracy. But 4+ MOA really is unacceptable.

 

[John C.]

What's particularly frustrating is that POF's have the reputation for being pretty accurate, particularly for a piston gun, with guys claiming consistent 1 MOA accuracy. And while I'm certainly no expert marksman, with my other AR (mounted with an ACOG) I can consistently hit 6" steel plates from 100 yards either prone or sitting. Right now I can't say this with the POF (unless I use match ammo at $1/round).

 

[mac1911]

I don't know what you should expect from a POF. Seems they build rough and tough guns by the description. All I can say is ARs where designed as axbattle weapon with good enough to "hit" target accuracy. I cant find the link but I'm sure if you go to ar15 or carbine.net you can locate the ammo test standards for military small arms ammunition. M855 is considered good @ 4moa the way they go about the testing groups can actually be large. I have not seen much on the new coated barrels that are being used to fight corrosion vs stainless or good old steel for accuracy.
Also in my limitted experience with ar and the world of moa. I can achieve 1" groups only off the rest on my better days. If the lighting is bad forget it.

For the price those pof guns go for when you called and they didnt say. "We test all our guns for accuracy with x ammo at x yardage and this is our standard" maybe its time to call back and talk to a tech... find out what their standards are.

As for shift in impact vs point of aim from ammo to ammo brand to brand lot to lot
That's to be expected. Especially with the changes in velocity. I have seen some 223 loaded as low as 2600fps vs the 3000ish m855 is loaded to. Never mind the cheaper stuff. I pulled 10 silver bear bullets 52,55and 62 grains al mixed in. And forget about the powder drops! Its all fun. Reload or find ammo it likes and buy a few thousand rounds. Or you can buy a rra national match with a stated 3/4 moa.

 

[Nuke8401]

Just a datapoint for you,
my 1-9,16" chrome armalite upper shoots bulk fed, xm193, 855 between 2 to 4 MOA.
with 55gr nosler BT(thanks Dan) or serria 69bthp 1 to 1 1/2 MOA.
I didn't see the twist rate of your barrel but 69 should work in a 1-9 but anything heavier might not depending on the specific barrel and other conditions.
Hornady bulk 55fmjbt are good for 2 MOA.
all are handloads using fired brass, trimmed, and reloaded on a progressive.
So my taka way is that the bullet is the key.

 

[xtry51]

The POI shift between ammo is completely normal. On accuracy I would expect if you sled your rifle with Black Hills 77 it will shoot under 1" groups assuming you don't have a high round count.

Military ammo is not accurate. The best group I've ever gotten from my 16" Daniel Defense 1:7 upper with M855 was 2.25" at 100 yards, but I've shot a .75" group with 77gr reloads.