AR Shoots to the Right

[castrotikon]

Buddy of mine bought a complete PSA upper from another guy he knows, first AR. I helped him assemble the lower for it and we hit the range to test it out. At 10 yards, he is hitting about 2-3" to the right of the bullseye. I can put a pretty tight group with it at that range but same thing, about 2-3" to the right. Standard A2 front sight, Magpul MBUS rear sight. I can push the rear sight almost as far left as it will go and can put shots consistently on the bullseye but that kind of change at such a close distance, particularly with just iron sights, makes me think something is up.

Am I mistaken thinking something is amiss? If not, what could potentially cause it?

[SpartyME]

Knowing PSA, the barrel nut is probably loose or the receiver needs to be lapped to the barrel.

[somecrazygreek]

I can push the rear sight almost as far left as it will go and can put shots consistently on the bullseye but that kind of change at such a close distance, particularly with just iron sights, makes me think something is up.

Am I mistaken thinking something is amiss? If not, what could potentially cause it?

Guns don't shoot left or right at different ranges, so that doesn't make a whole lot of sense.

Are you using the small aperture to sight it in? Or the large one. You're supposed to use the small one, lots of people don't know that.

Also, finger placement. Are you shooting with the pad of your finger?

There's also the fact that it's PSA. I have never had issues with their stuff but some uppers definitely slip through the cracks.

Finally, keep in mind that a lot of people buy chinese knock off Magpul MBUS sights on Ebay that look mostly the same and those are known for not sighting in worth crap.

[Rootsy]

FSB isn’t indexed properly (it is set then drilled and pinned in one setup) or the rear sight isn’t actually on receiver centerline.

[JohnJak]

Replace the plastic MBUS with a metal one.

[Moleman-]

As much as I'd like to dislike PSA my impression of the kits I've bought from them has been that over the years I've paid more for worse quality. Certainly not the best but not near the worst. I'd agree with others that the first thing to check is the plastic "magpul" sights being an airsoft/copy version. Google images has a decent side by side of the differences between the real and fake ones. If that checks out check to see if the front sight is canted.

[JohnJak]

When torquing the plastic MBUS down it tends to cant/lean.

[TylerV76]

Every Magpul Mbus rear sight I have bought and used has had to be set all the way left to be accurate. The ones still on my Colt 6920 are that way as we speak. Ive talked to a good number of folks on here that had to move theirs all the way left as well. If thats gonna be an issue then you're gonna have to get better sights.

[Quads]

Remove, inspect, and re-pin the FSP, then replace the plastic junk with something straight.
https://www.midwestindustriesinc.com...is-pkg-fde.htm

Take the barrel off, clean, inspect the extension and ramp, lube, reinstall / re-torque.

Choot-it.

[JimSig]

Try to mount a red dot that is already zeroed on another AR. I bet you that it will shoot center. The problem might be from the installation of the rear mBUS sight. It could be swayed to the right by the way it was attached (or by design) and that's why it is shooting to the right, and accordingly you keep dialing the rear peep sight all the way to the left to correct it. As I said, if you try to mount a pre zeroed red dot on it, if it shot in the middle then it is the rear sight (or the front sight is canted). if it did shoot to the right then there is a misalignment some where in the upper that is beyond my level of knowledge.