Some time ago my good friend Ray gave me an RCBS 30-165 Silhouette two cavity mold that had a stripped handle screw. He needed handles remoneved and the problem solved so the handles could be used on other blocks. While I had the mold I cast 300 or 400 bullets. The mold dropped bullets at .310” with my mutt bullet trap alloy. Ray had put a mark in one of the cavities to identify which cavity a bullet dropped from. I shot quite a few with so-so results from several .30/06 rifles and a .308. 10 shot groups were anywhere from 2-5 inches at a hundred yards depending on the rifle and load. That was 6 or 9 months ago.
During a bench cleanup I found about a 100 of these bullets as cast in a box. I decided to lube them in a .310 die and seat gas checks on them. I then loaded 40 of each bullet and shoot them separately. Wow. I’ve never done this before and what a difference! The marked bullets averaged 4 moa for ten shots and the unmarked cavity bullets averaged 1.6 moa for 4 ten shot groups each. All were fired on the same day from an 03 Springfield sporter with a 6x scope. Each string started with a clean cold bore and each ten shot group was shot alternating the bullet type. I was amazed with the difference. I should have know because my best groups have always come from bullets cast in single cavity molds. Another avenue to try with some two cavity or larger molds. Two sample targets are below
