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View Full Version : Upper Picattiny Rail Slot Issues & Potential Solutions



LaTecTex
09-04-20, 16:45
Have any of you ever experienced an upper receiver were the picatinny rail slots were too tight preventing the use of optics? If so, how did you resolved the issue?. Of note, I am keeping the manufacturer of the upper receiver group undisclosed until I hear back from them about my issue and their thoughts on addressing it.

Recently I picked up an ACOG in a Geissele scope to put on an A4 upper receiver group that I've had for going on 6 years now. Until recently I have had a Aimpoint CompM2 on a LaRue M68 mount on the rifle, and I had no issues with the rifle. When I took the Aimpoint off an tried to put the ACOG towards the back of the rail, but forward enough to clear my BUIS, I could get the scope on, but only with trouble, and when secured, with a noticeable gap between the mounts lugs and the rail itself (click the below image to see). My concern is that the mount is not properly secured and that my reticle's BDC will be off because of the gap.

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When I removed my BUIS and tried to mount the ACOG as far back as possible, I couldn't get the mount to engage the rail at all; highlighting that the rail had issues with slots T1 through T6. When I try the mount on the quad rail installed on the rifle it links up just fine, and it also attaches to other uppers with relatively ease as well. Just to make double sure that it's not an issue with the mount, I tried mounting a LaRue LT-105 and it too has significant issues.

As stated in my intro, has anyone else had a similar issue, and how did you address it? I'm curious in your experiences and whether or not this is common as I wait for a reply from the manufacturer.

militarymoron
09-04-20, 18:06
It's not common, but happens. You're doing the right thing by contacting the manufacturer. If it is indeed out of spec, the manufacturer should swap it out.