How likely is it that my scope is the problem?

[SuperSneakySniper]

Sup guys,

I'm firing one of my new ARs (never fired before) at the local range yesterday, and WHAT THE HELL? All I wanted to do was zero the guy in at 50 yards, and it wouldn't do that.
What I mean is right from the get-go, I'm seeing nothing but random flyers everywhere, generally I'm getting 3-4 inch groups at 50 yards, which is beyond unacceptable.

Now, I will admit, I only had some cheap American Eagle ammo on hand, but even then I thought these groups were a little ridiculous, my good o'l trusty BCM was grouping under an inch at 50 yards with the same ammo with no drama.

About 2 boxes in, and it starts acting passive-aggressively. Two or three shots will group nicely, about an inch or under, and then BAM, a flyer about 3 or 4 inches to the right, then BAM another flyer 2-3 inches to the left, and I'm left scratching my head. Then the very next 3 shots group nicely again, and then the following 3 group nicely... except they're now 2 inches high and to the left...

This is a 16 inch .223 Wylde Strike Industries Strike Fighter Barrel, a 2A armament RBC bolt carrier group, and the barrel nut is torqued to about 35-40 foot pounds. The sight was a Primary Arms Gen3 1-6x ACSS scope in an Aero Lightweight 30mm mount. Yes, I know my scope setup is on the cheap side, but I have used Primary Arms scopes in the past for budget builds and they do just fine for local/fun stuff.

So what do you think guys? Is it more likely that my scope is all funky? Or is it more likely the barrel is to blame here? I pulled the scope off and will try that next time I go out but I won't have time for another range day for a while.

 

[demolitionman]

Uhhhhhhhh....take the scope off the BCM. Place it on the trouble Ar and try again.

 

[bfoosh006]

Frankly, even crap scopes will group better then that.... IMHO, Primary Arms sells good enough scopes, I have many of them.

I would double check all the mounting screws. Something is loose.

Double check everything is tight enough... flash hider, barrel nut, gas block. etc. ... in particular if it only happens after it heats up.

Look for any interference between the FF tube and gas block ( GB bonking the inside of the FF tube, or a mount screw from any add-ons ) or wildly too snug standard handguards.

And be sure to take some other ammo to try... it is "possible" your barrel is not in spec, or has a defect that is causing the ammo jackets to be nicked or such.

Run a tight fitting cleaning patch down the bore, carefully "feeling" for binding or something not right.... you can feel if there is something not right.

 

[Yondering]

Now, I will admit, I only had some cheap American Eagle ammo on hand,

While the scope or scope mounting certainly might be the issue, and that is a common enough problem - I'd still try some decent ammo before anything else.

A while back I sold a friend a spare AR - nothing special, just PSA parts mostly, but it shot well for me. He reported about the same thing as you, also with cheap American Eagle ammo; poor accuracy and inconsistent groups. I gave him a handful of my own good loads and he immediately put 5 rounds in well under 1" at 100 yds.

Sometimes the ammo really is that bad, and not all "match grade" ammo shoots well either.

The recommendation to just swap scopes is a good one though, and easy to try on the AR. You don't even need to adjust the zero to find out if that's the problem, as long as it's on paper.

 

[SuperSneakySniper]

While the scope or scope mounting certainly might be the issue, and that is a common enough problem - I'd still try some decent ammo before anything else.

A while back I sold a friend a spare AR - nothing special, just PSA parts mostly, but it shot well for me. He reported about the same thing as you, also with cheap American Eagle ammo; poor accuracy and inconsistent groups. I gave him a handful of my own good loads and he immediately put 5 rounds in well under 1" at 100 yds.

Sometimes the ammo really is that bad, and not all "match grade" ammo shoots well either.

The recommendation to just swap scopes is a good one though, and easy to try on the AR. You don't even need to adjust the zero to find out if that's the problem, as long as it's on paper.

Fair enough. I'll go ahead and swap sights and pick up a box of better ammo, as well as more of that American Eagle to use as a "control group", no pun intended.
The main reason for posting this question was to see how likely that the barrel itself was whack, but it doesn't seem to be a prominent suggestion so hopefully it's okay.

 

[Nik H]

I went to the range today with my AR15 and to do some shooting at 100 and 200 yards. I put a new scope on my rifle and wanted to zero it and just have some fun collecting DOPE with a couple of types of ammo. I had some American Eagle 55 gr FMJ-BT rounds and some match ammo from Black Hills using the 77 gr SMK pill. Use the AE to get on paper and then fine tune with the BH. The consistency of groups at 100 yards with each type of ammo was obvious. You get what you pay for.

Moved to 200 yards. When I was using the AE ammo, I was really struggling. I fired 10 shots and had a 2.5 MOA group at 200 yards. I was like....huh?

I fired 10 shots of BH and it was 0.6 MOA.

The American Eagle ammo is plinker ammo not anything you should use when zeroing a scope.

Problem is that you are seeing this at 50 yards...not 100 or 200. That sounds odd to me. Try the ammo first. Make sure you buy a cartridge with a bullet weight compatible with the twist rate of the barrel. Secure the mount to the receiver with a torque wrench and then torque the ring screws as well. The outcome of this test will tell you what to do next.

 

[maggitas]

check gas block, check alignment of gas tube, remove flash hider and fire weapon. Double check scope and scope mount. clean barrel and chamber.