I have recently purchased a 20" upper off of the EE and it came with a BSA scope.

When I went to the range (indoor) I zeroed for 25 yards. (I know, I know, I just wanted to get a feel for the weapon) But when I extended to 75/100 yards, the rounds were high and to the left.

The scope is mounted with two individual scope rings, onto a flat top receiver.

Is there something I need to do to mount the scope better? I have heard of AR mounts that have an angle built into them, is this what I need?

I am looking to make this a (relatively) long-range weapon. Any help will be greatly appreciated.

did you try to re-zero it?


bsa scopes arent known for their quality or their ability to hold zero.

If it's zeroed for 25yds, it'll shoot ~4.5" high at 75yds and ~6.5" high at 100.  Doesn't explain shooting to the left, but a small error at 25yds would be 4x as much at 100 so maybe you just didn't notice it at 25.  Re-zero at the longer range and see if it holds there.

It's also possible that you're getting some parallax error from not being able to get your eye behind the scope consistently.   I have scopes mounted with rings on the receiver and it's OK for lower-power scopes but not really quite high enough for bigger ones.  I had to switch to the Armalite one-piece mount to get my 4-16x where I could really use it at 16x.  I've been quite happy with it and so has my dad who also has one on his AR.    IMHO the similar RRA mounts are too high.  They also lack the forward offset that helps get the eye relief right.  

Quoted: I have recently purchased a 20" upper off of the EE and it came with a BSA scope. When I went to the range (indoor) I zeroed for 25 yards. (I know, I know, I just wanted to get a feel for the weapon) But when I extended to 75/100 yards, the rounds were high and to the left.

If you zeroed at 25y the rounds SHOULD be high (on the order of 6"+)

But I also concur with Eklikwhoa's comments on the optic.