Hey all,
I seem to be having issues with my Eotech 512 sliding rearward on the top rail of my upper receiver. When I mount it to the rail I make sure that it is seated all the way forward, then I torque it down. It seems to always want to walk back an 1/8 to 1/4 inch after 100 rounds or so. I’ve tried sinching in down as tight as I feel comfortable without over tightening it and breaking something. The rifle is a Smith and Wesson M&P15. Any thoughts or ideas on how to correct this?
It could really be your S&W rail being out of spec as well, is it a sport?
Are you using the thumb screw or the Allen head bolt. Are you using some blue locktite?
Using the thumb screw tighten it as tight as you can with your fingers. Grab a flat heat screwdriver and just snug it a tad tighter. That, with some blue locktite on the threads shouldn’t move on the rail no matter where you put it. Or your rail is out of spec. But the eotech should have enough adjustment. Should…
Tighten it. Use Blue Loctite. It won’t slide unless something is wrong with your upper.
Not a sport. It has a dust cover and F/A. I’m using the hex bolt and not the thumb screw. Like I say I’ve cinched it down as tight as I feel comfortable. I don’t think Locktite will help as the screw is still very tight when I go to loosen it to reposition the sight. I’ll give it a try though, stranger things have happened!! I really hope its not the rail being out of spec.
If it’s moving an 8th to 1/4 inch something is very wrong. The cross bolt to slot fit shouldn’t allow that much movement. Try tightening it while sliding it all the way back. The impact of the bolt going into battery is sharper than the recoil impulse in light caliber rifles. That’s why air guns are so hard on scopes.
Are you sure it is a real Eotech?
Yes it is. Purchased from a local brick and mortar police equipment store. Serial number registers with Eotech as well.
I was thinking the same thing. I’m going to try the thumb screw with blue locktite and if that doesn’t work I’m going to try what you suggested. Thanks.
Layer a little aluminum foil on the rail to tighten it up. Silly simple trick but it works.