Thread: Slipping scope

hi guys and gals. I'm brand new here, but wanting some advice. I bought a 1952 sporterised 303 with a 4 x 32 tasco scope. When trying to zero in the scope, I discovered that after about 5 rounds, the scope had moved to the rear of the scope rail. Another 2 rounds saw it sliding right off. Put the darn thing back on, checked the tightness of the screws, but 5 rounds later, the scope was at the back of the rail again. Has anyone else experienced this, or has a suggestion on a fix, short of welding the scope to the rail? Cheers.