AR problem- can't get on paper

[bearintex]

So I finished my 6.8 AR build a while back and finally got a chance to go to the range yesterday. Imagine my dismay when I couldn't find the paper at 25 yards. Hitting way low and left. Maxed the scope out to correct it and still about 6" low left at 25. Is it possible to get the barrel cocked when the barrel nut goes on? I wouldn't think so. Going to throw another scope on first to rule that out.

[Paslaw0311]

Ive had that happen with 5.56's. One piece scope mount or two piece? I removed, and re-mounted scope and it fixed my issue. Do you have a set of irons to mess with before the magnified optic? I would think it would be easier to tell if its a gun or an optic problem without any zoom.

[Brhibler1]

Open sights first, then scope.
Try a paper bore sight.
Local range here has a 8" target with a cross drawn at top. You center your bore with target rings then look through scope and adjust accordingly.

Second remounting, you might find your problem.

[bearintex]

I don't even own a set of irons. My eyes don't like them. I plan to pull a known good scope/mount combo off my 556 and try that.

[iamntxhunter]

Remove your bolt and set your gun in a vise of some sort so it is stable. Set your target up at 25 yds and then position your gun so you can see the bullseye through your barrel. Without moving the gun adjust you crosshairs so that they are on the bullseye as well. This is just a cheap and simple way to bore sight it.

[sniper steve]

6" low at 25 isn't that uncommon, depending on the height of your scope mount.

I'd remove and remount the scope, using bubble levels to make sure the scope is properly set in the bases. Go the 100 yard line. Use a 6" bright orange or other easily visible target. Remove your lower and BCG, allowing you to look down the barrel. Put the upper in a lead sled, or sand bag it. Center your 100 yard target in the barrel as you are looking through it. Then adjust your scope to the center of the same target. Easiest, best way to bore sight a rifle I have ever found. Put your lower back on, and you should be pretty darn close.

If you are still way off target and running out of adjustment, look into new mounts. Even the slightest imperfections with your scope or mounts amplify themselves greatly as you get farther out.

[Ecoboost]

What mount are you using?

[rcjunky007]

What scope mount are you using?

[bearintex]

Think I found the problem. I took the upper off, pulled the BCG and set it up on a bipod and bags to hold position. Tried to boresight it looking down the barrel at a light about 300 yards away. Couldn't get within 10 feet of it. Take it back into the shop and start looking it over with a fine toothed comb, and notice the mount is askew on the receiver. Unbolt it and find there is a small piece of grit or something underneath it. Remounted and back out to the bipod/ bags and it came right in. Off to the range tomorrow morning to verify.

It is a CCOD one piece mount, with a CCOD 3-12x40 scope in it. Upper started as a factory bushmaster, but I swapped barrels to an SW MP Sport I had (I wanted the 223/ 5.56 to have ejection cover and forward assist, which the Sport doesn't have). I also shaved the gas block and put on a cheap free float modular rifle length forearm.

[bluelund79]

I hope that was all that was wrong. Sometimes a simple and easy fix is a nice way to solve a problem.