I was lucky and bought a small stock pile of Burris Zee Rings when they were on sale for 20.00 a set.

My biggest observation with scopes on heavy recoiling rounds parallels Greggs somewhat. I found on really heavy calibers I was having problems with aluminum basses, even with 4 Burris Zee rings. Now that could be because I was using 4 standard sized screws with the base as well.