AR zero issues

[Girth6]

Ok AR experts I have a buddie who got a new smith AR15 sport. We put my old 3gun scope on it Burris 1*4 and can not get a consistent zero at 50 yards the rounds are all over the road using a sandbag for support. Thinking my scope was bad we remounted it on a old stag I have. And bingo 1/4 inch groups off the sandbag. So if the scopes good what are some things we can look for on the AR before sending it back to smith.

thx in advance

 

[T.Lex]

How are you mounting it? (Or just shaking hands?)

Also, what kind of handguard -freefloat?

What ammunition? Try different kinds? Try same kind in your Stag?

Any BUIS or other optic you can try on the Smith?

And I'm not even near an expert.

 

[Girth6]

Same ammo 55g federal, free float hand guard. We're not talking 3 inch groups were talking it's off by a 12 inches from shot to shot. Mounting it on sandbags shooting prone (I know not the best buts it's all that's available).

 

[SEIndSAM]

See if the barrel nut is loose.....
Can't remember where I heard this, but somewhere I read a similar problem with an SW Sport and that was the issue...

 

[T.Lex]

Mounting it on sandbags shooting prone (I know not the best buts it's all that's available).

Sorry - I meant, how is the optic mounted to the Smith AR? Same rings used on the Stag?

And 12" groups?! Dang. Yeah, that sounds like something more fundamentally wrong with the barrel, if it isn't the optic.

 

[Mr Evilwrench]

The scope mounts to the upper, and the barrel mounts to the upper, vs most rifles where the scope mounts to the barrel. If either or both are loose, you'll get what you're getting. The only other possibility I can think of is the upper is cracked and held together by the lower, scope and bolt carrier. You'd think you would see it, and I'd be genuinely surprised, but with some of the wild stuff I've seen I wouldn't say impossible.

 

[sloughfoot]

What bore is the rifles barrel? We never had to think about this b4 6mm, 300 Blackout and everything else. Easily checked with a bullet in the muzzle,

Something is loose or out of spec.

 

[Hookeye]

I thought the M&P sport did NOT come with FF handguard.
If somebody changed it, I'd double check their parts/workmanship.

 

[tradertator]

Sounds like something is definitely wrong with the rifle. I would look down the bore, make sure it doesn't have any burs or debri in it from being manufactured. I'd also check the barrel nut and make sure it is on there right.

 

[AA&E]

Many factors... barrel twist/ammo combo. Scope mount issues (especially if done on cheap aftermarket freefloat quad rail). Damage to the barrel rifling/crown. There are a lot of things that have to come together to make an accurate rifle.

 

[Jeremy1066]

A sport model would not come with a FF handguard, which means someone added it. Unless they used a Samson/Fortis/Alpha/etc. that uses the factory barrel nut, the barrel came off the receiver. I'm guessing a less-than-qualified gunsmith is to blame.

 

[RobbyMaQ]

That seems really off, even for a crappy scope. Same shooter off that much? Or are you switching shooters and it's off that much? (even so, the latter is kind of off a lot).

 

[Bfish]

See if the barrel nut is loose.....
Can't remember where I heard this, but somewhere I read a similar problem with an SW Sport and that was the issue...

Any word on this OP? I was thinking the same thing... If the optic and the mounting of it isn't the issue, this is what I thought of but who knows. I've never had any experience with a loose one, but it's what I also thought of and so I agree with SEIndSAM

 

[Girth6]

Talked to smith and there taking the rifle back to look at it, very impressed with smith and Wesson customer service. Thx all I'll let you all know what they say

 

[Bfish]

Talked to smith and there taking the rifle back to look at it, very impressed with smith and Wesson customer service. Thx all I'll let you all know what they say

Good to know, thanks for the update!

 

[tbhausen]

So, did anyone work on the rifle, or was it still as it came from the factory?

 

[Girth6]

Nope it's as is from the factory, and my bad meant to say no free float handgaurd.

 

[jonny4523]

If you're serious about 12 inch groups at 50 yards, my money would be on a loose barrel nut.

 

[Girth6]

Buddie got word from smith there sending him a new rifle, he said that the old ar had in Smiths words "Barrel issues".

dont know what that means but cudos to smith and Wesson for great customer service.

 

[hooky]

Glad it got resolved. I was going to suggest checking the choke tube. Sounds like a Modified and you probably should be shooting a Full.