AR15 zeroing help

[jrinne0430]

Background:
I am still learning the ropes on ARs and recently purchased a PSA in the M4 config with flat top receiver and fixed front sight. It has a UTG flip up rear sight with both sight apertures.

Issue:
When zeroing at 50yrds using surplus M855 ammo, I had to move the rear sight 20 clicks to the left (no far from maxing out). Is this normal or would it indicate something is wrong with the sight or the rifle?

 

[Sweet Shooter]

I think if it works it works, but very unpleasing for me.

There are variables that need to be addressed.

Try turning the UTG piece 180 degrees—so install it backwards. See if the same amount of windage is required in the opposite direction.

If it is, then your fixed front (pinned A2? you didn't say) may be installed tilted.

Does this rifle have M4 feed ramps in the receiver? how do they line up with the barrel extension ramps? It could be that your barrel index pin is over to one side in the slot. That can be fixed fairly easily if you have an AR armorer's wrench. I believe this is easier to fix than the sight being out true on the barrel.

Though you can get lucky, I wouldn't go a bundle on UTG to get much straight. Could you (borrow) try a different rear sight by a more reputable maker? I have not known an rear MBUS not to come up straight.

-SS-

 

[Lt. Skrumpledonk Ret]

No. It happens.

 

[jrinne0430]

It has a pinned A2 front sight (appears straight) and M4 feed ramps that appear to line up with the barrel. I was considering purchasing another BUIS but did not want to spend the $ if there is something wrong with the rifle.