I am soon to receive a JM 336 30-30 and was planning on shooting cast bullets. I posted this on the Marlin site also. This is a Gunbroker purchase and won't receive it until later next week. However since the purchase I have heard that the Micro groove rifling and cast bullets aren't the best combination, I cast bullets. Does anyone here have any experience with cast bullets and the Marlin 336? I much prefer Lee molds. Most of my shooting is just fooling around type of stuff. If I have to buy-God Forbid-factory rounds for hunting I may have to do that. Thanks Dave