Actually Triple, you were right the first time. A shorter nipple might work. The lead edge of the hammer lip nicks the muzzle edge of the cap, but the internal face of the hammer strikes the back edge of the cap/nipple causing ignition. If the hammer had a hair further to fall it would land more squarely on the cap and nipple. I'll have to try that. What's the hottest nipple out there and why would I consider anything "cooler"?