SKS Scope Base Receiver Cover

A couple months ago, I found at a pawn shop a good deal on an SKS receiver cover with a permanently attached Weaver base, and a 1" diameter fixed 4X rifle scope, with rings, ready to stick on an SKS rifle.

The other day I mounted it on my Norinco SKS, but the cover was a very loose fit. I didn't even try to shoot it, because I guessed I'd be getting a foot of crosshair movement at 50 yards just based on the wriggling of the receiver cover.

So then I shimmed it. I added strips of aluminum tape (real duct tape) to the forward rails underneath the cover, with strips of tape about 1.5" long and maybe 3/16" wide.

Then the reciever cover fit TIGHT. I was happy. I thought I had fixed the problem. And I was so confident, I didn't even try to work the rifle's action or do some dry fire practice at home before going to the range.

At the range, I found the shims interfered with the bolt carrier. The rifle could not be fired, as the bolt would only go back about halfway.

I also noticed that the scope extended over the rifle's magazine loading area. Not a big deal for target shooting or hunting, but it would interfere with rapid reloading in a combat situation. No way to use stripper clips while the rifle is wearing a traditional 10" long rifle scope either.

QUESTION: Have any of you had to shim or add material to a too-loose SKS receiver cover? Do you have any suggestions for what might work better than aluminum tape? Maybe use some 2-part epoxy and then after it hardens, grind or file down the excess to make a custom tight fit?

P.S. I think my SKS is accurate enough to justify a crosshair scope, at least a cheap 4X one. With Wolf or milsurp ammo, I can shoot about 5" groups at 100 yards with iron sights. I imagine with Remington or Winchester commercial soft-point hunting ammo, accuracy should be even better. What I'm trying to accomplish is make the SKS easy to hit deer-sized targets (vital area, center of mass hits only) at up to 200 yards, or varmint / predator sized targets (coyote, woodchuck) at 100 yards.