Home Forums Hunting & Shooting Hunting Rifles Shiny liner between action and scope base???

I bought this custom 375 wby a couple years ago. I was going to switch the scope base around so it didn't hang over the port as much. When I removed the base, it had this shiny material stuck fast to the action. I've never run across this, anyone know what it is/what its purpose is?

Looks like a redneck base shim out of a cardboard/business card type material.

+1 definitely a bad attempt at a shim. I'd get rid of that ASAP. If fit isn't good you can skim bed or buy some other bases and rings.

It looks tan in the pic, but its a reflection of the wood shelf above it, sorry. It's actually silver/mirror reflective metallic material, with blue writing on it that I can't make out.

The black squares line up perfectly with the screw-holes, almost like it was manufactured for this application.

Looks like shim-stock, most likely as others have said, to shim the base. You can get it in brass, aluminum, stainless, carbon steel, etc. It looks like you can still see the markings on it, which will list the material, thickness, and other info.

Bad shim job, you could bed the new mount to the action and call it good.

Thickness might be needed, particularly for things from the pre CNC era, and scopes without a lot of adjustment or they may be the wrong bases with differences between Mauser actions. It looks like laminated shim stock, which is great stuff in some (aerospace) applications.

Steve- this ^^^