Thanks for the replys. My USPSA/IDPA is Clays and I use a 18½ lb mainspring for major, which is the reason for the question. Bullet casting is another hobby of mine, but might have to go to jacketed because or the lube smoke. We used to hold IDPA matches inside, and the smoke was thick, we put on the fans and all the heat would leave also. I shoot .22 indoor rife and pistol league at another indoor club, it is lots of fun, and keeps the skills up during the winter.