AR15 sightning problem (not enough windage)

[Snake.Doctor]

Hi Guys,

Today I just finished my latest project, it's an 11.5 SBR on the AR15 plateform.

So I went to the shooting range to sight in the rifle.

The rifle has a free-floating 11.5 barrel with a DD Mk18 RIS II handguard.

The target was 25 meters away, and I directly sighted the Eotech in. After 2 groups, I was able to get very tight groups consistently, centered. Everything was great... Until I decided to sight in the mechanical sights.

Flip-up sights are from Troy Industries. I had very good results with them at 300 meters on an M4 carbine. The problem here, is when I wanted to co-witness the Eotech reticle with the mechanical sights. I don't have enough windage on the rear sight to match the mechanial one with the holographic one...

So I'm trying to figure out where the problem is ? There is no front-sight block which could be canted, I was thinking could a bad indexed barrel produce this, but since it's free-floating and the sights are only on the upper receiver and the handguard ???

If anyone can help it would be great.

Thanks

 

[rjrivero]

Make sure your handguard is on square to the upper receiver. If it's canted, you'll screw yourself trying to get things lined up.

 

[Snake.Doctor]

I just measured the exit of the barrel through the handguard, and the barrel goes to the right :

I have 0.7335inches from barrel to handguard on the right, and 0.780inches from barrel to handguard on the left.

 

[rcmodel]

Has to be crooked upper receiver barrel nut threads.

Or crooked handguard or nut threads.

Or a chip or bur under one of the seating surfaces.

I'd take everything back off and look for a bur or chip under the handguard nut or barrel extension flange on the left side that might be cocking the barrel out of line in the upper.

rc

 

[Snake.Doctor]

I disassembled the handguard from the guin completely, and the nut was a little canted.

I reinstalled everything and now the mechanical sights are aligned with the holographic one perfectly in the center !

Thanks !