Cutter,
I have never seen this warning against CCIs of which you speak. 0.o
I'm definitely with you on careful primer seating. I also mechanically set depth/limit arm extension though.
JMG8550,
I've never had a CCI fail me either.
I would say that you would probably see gains from switching to the regular CCI or other primers though. If you're getting 3/4 MOA using those primers you're doing well. May I inquire as to your load and gun, and the number of shots in the string you're mentioning?
I get quite bored sometimes, which is usually followed by getting quite eccentric, and I test/meddle with things extensively. I've never been able to get a good SD, and hence comparatively good grouping, from the CCI Arsenal primers; I have no informed guess as to why. To further clarify, we're talking in 10 round strings out of Noveske AR-10s and 15s.