If you want to size your cases and not shrink it down any more than possible - Start with a fired case. Back off your full length die a full turn from the shell holder when the ram is all the way up. Lube your case well, but not too much. Run your case in to the size die all the way up and with draw it. check to see if it fits in your chamber. More than likely it will not. If it does you will need to start over with a different case and back off your die even more. Assuming you do not have to back the die off any more - turn the die 1/32 of a turn and resize your case again. Try to chamber the case. Repeat until the case will JUST fit into your chamber and close. Now take another fired case and run it into the die, lubed of course, and then check your setting to make sure the case will just fit your chamber with out adjusting the die down any more. If every thing is right, tighten down the lock ring. Remove the die and set it back in and size another fired case. If it still chambers with out having excess head space, you have just custom set your die for your chamber. You can now size all your cases and not push the shoulder back too far, causing it to stretch excessively. This works well for break open single shot rifles like the Handi, Rossi, and T/C rifles to mention a few. Even if your gun has excessive head scape, once you have your dies set, it will work fine and should let your cases be loaded for several more loadings than a full length sized case. Good Luck and Good Shooting