Accuracy issue... But possibly just me?? (bullet weight -vs- barrel length)

[90lxracer]

After my requisite wait for the ATF to do their thing I was finally able to take my AR-15 conversion home...

Well, I took it out for the first time and I wasn't really "impressed" with how it shot. The guy I bought it from kept the sights so, I put of set of PSA aluminum flip-up sights on it, and was only shooting at 25 yards. But the groupings (if you even want to call them that) were horrible!

I was shooting from a seated position, and was reasonably well supported. As I was using a table, a shooting block to support the front of the gun, and I could get my elbows on the table from which I was shooting.

My question/s are: How much does bullet weight affect accuracy when dealing with short barrels?

The gun had a 10.5" piston upper (I don't know the twist off the top of my head), and I was using a bulk type FMJ 55 grain bullet. When I originally shot the gun before purchase, the guy I bought the gun from brought ammo, and was using a 62 grain FMJ.

Can a barrel be that sensitive to bullet weight? Or was I just THAT far off??? :fie:

[Clint]

Welcome to the forum.

Was the guy selling it due accuracy issues?

At 25 yards, I'd expect must any AR to be drilling a quarter sized hole, even with crappy ammo.

How big was the pattern?

It really could be anything from loose barrel nut to flared or chipped crown or some piston issue.

Retesting with some 75gr match type ammo should show something.

More info would be helpful, especially with a non standard piston conversion.

[markm]

Try different ammo.

[90lxracer]

Welcome to the forum.

Was the guy selling it due accuracy issues?

At 25 yards, I'd expect must any AR to be drilling a quarter sized hole, even with crappy ammo.

How big was the pattern?

It really could be anything from loose barrel nut to flared or chipped crown or some piston issue.

Retesting with some 75gr match type ammo should show something.

More info would be helpful, especially with a non standard piston conversion.


Thanks for the welcome!

I don't believe he was selling due to an accuracy issue. He told he was selling to raise a bit of money for a belt gun purchase.. I don't really have reason to believe otherwise.

At the time of the original shoot, I was really just making sure it ran full auto, more than driving tacks.. lol It was NO WHERE NEAR a quarter size groups! lol (honestly a bit embarrassed to say how big!)

I would have to get with the guy I bought it from to get the spec's on the upper. I had them at one point, but I don't anymore. I would have to get some heavier bullet..All I have right now are 55 grain. Darn.. a reason to go buy more ammo!! lol

I could try a couple things... different upper : may rule out bad ammo, But they're longer, the only other "short" barrel I have is in 300blk. Then the different ammo, on same barrel.. I can take the current upper apart, and see if I see anything as well..

AND I haven't shot in about a year, year and a half.. but I honestly don't think I'm THAT bad... but maybe! lol I have shot sub 1 MOA @ 100 with a different AR-15 I have, but that one is set up for varmint hunting.. 20" bull barrel, and nice 2 stage trigger, and decent scope

I was just wondering if barrel lengths could be that sensitive to bullet weight? Sounds like more shooting investigation is needed... bummer :cool: lol

[markm]

I was just wondering if barrel lengths could be that sensitive to bullet weight? Sounds like more shooting investigation is needed... bummer :cool: lol

Generally no. If I'm reading you right, you bought a transferable MG.... so you can run any upper length/caliber you want.... Upper halves are pretty cheap in the current market... Or a barrel replacement. Those are cheap compared to the price of a transferable.

[90lxracer]

Generally no. If I'm reading you right, you bought a transferable MG.... so you can run any upper length/caliber you want.... Upper halves are pretty cheap in the current market... Or a barrel replacement. Those are cheap compared to the price of a transferable.

Yes, this is a transferable MG. The upper is just an upper as far as I'm concerned. I'm not married to it, I have plenty of others I can put on it, OR just go buy another shorty 5.56 one. And in relation to what the receiver costs, buying an upper is a drop in the bucket.

And it could very well be just an issue between the gun and the chair! lol Just more reasons go out and shoot more!