Went to the range this evening to get my RDS and BUIS sighted in on a new rifle that I built earlier this winter. The red dot was great and was pretty much on target from the beginning. The BUIS were a problem though.
First, details on the rifle. The upper is a PSA premium 16" mid-length with an A2 front post and the rear sight is a PSA branded aluminum that cost about $40.
As it stands now, the A2 front post is down as low as it will go and the rifle is still shooting about 3-5 inches low at 25 yards Edit: front sight will go lower, I was mistaken about that. Also, I had to move the rear sight pretty far to the right to get the windage lined up. Pictures of both the front and rear sight in the positions I described are below. I’ve also included a picture of a target I was using. Blue is the BUIS and purple is the red dot. POA for the BUIS was the center bullseye and POA for the RDS was the upper left bullseye. (Take it easy on my group sizes. This is my first rifle and I know I have a lot of work to do regarding accuracy.)
Based on the alignment of my BUIS is there a problem with them and if so which one is it most likely to be? My guess would be that the rear is messed up but I don’t know for sure.
I also included a picture of the range. As I said I was shooting at 25 yards and it was slightly up hill.
I can take additional pictures of the rifle if they are needed.
Funny, a friend’s psa upper had the same problem. Swapped out the sight post with another upper and it worked fine. Try removing and reinstalling the rear sight, something may be off… try another rear if you have access to one.
As others have said, make sure the rear is staying in place. And just fyi, you are not even close to bottoming out the adjustment for your rear for windage so I would not worry about that.
Yeah you are right about the rear sight and the front was the same as well. I was using a 5.56 cartridge at the range to depress the detent and once it got low enough the bullet wouldn’t depress it any further because the bullet was too fat. I mistakenly thought the sight had bottomed out. I just checked it with a punch and it’s got quite a bit left to go lower. So I feel better about that part now.
I’ll reinstall the rear sight next time I go to the range and see how that does. Unfortunately I don’t have any other rifles or rear sights that I can test things on.
Weird that two PSA rifles seem to have the same problem. I’ll report back on how it does next time I shoot.
Also, see if someone else can try and replicate the problem at the range. Get some bags to sight your rifle off of. At 25 yards you should be easily able to drop rounds non-stop into a quarter easily. If not, there may be something else going on.
After thinking about it, mine may have been slightly different. I think the threads were not cut deep enough on the sight pin on mine, up near the top, limiting the travel. It worked ok in another rifle and may have been a tolerance stacking issue?
