Originally Posted by
Mauser308
Snapping screws and coming loose can be a sign that the rail or bases aren't properly fitted or you are getting uneven stresses on the mount system, especially with the big heavy calibre rifles like the win mags and RUM's or Lapua offerings.
Properly bedding rails to reduce the stress helps, that pretty much requires a two-part tapable epoxy to custom cast the shims under the rail. If two-piece bases aren't in line there isn't a lot you can do, some receivers don't like some base setups. Try another and that's where the one-pack Loctite adhesives help. Using Loctite on screws doesn't help much if the screw bottoms out, check that before fitting. Also, less is better than more, too much Loctite can stop the product curing (found that the hard way).