Crud ring does diminish - but since breechplug designs are all different, you really need to experiment in order to find the correct answer to your question. Yes... the new primers are worth the $5 investment - because in a majority of bores, they work just fine with pellets. The 2nd/3rd best controller of crud rings is a bore brush and a dry bore... meaning no lubes, oils or harsh solvents inside that bore when firing. Swab with big patches and Windex.