I used the 3M or Scotch tape headspace check method on a sporterized 95 7x57 Mauser. Cutting the tape to fit is kind of tedious. I forget how many layers of tape is considered safe. It checked out ok but I remember I had a loose primer or two with some 175 RN bullets and 4064.
I ended up shooting nothing in it but lighter loads with firefomed, neck sized brass. If I had it do again I'd take it to a gunsmith and get it done right.
