As you probably already know, I like to reload ammunition. It is fun and challenging. I get a lot of satisfaction out of reloading a group of cartridges and ending up with nice, functional and good looking group of rounds.

Today's exercise is looking at the effect of neck expanding and crimping with a .38 Special cartridge. There are three steps to reloading straight wall cartridges, resizing, neck expansion and bullet seating. Neck expansion is just to open the end up far enough to accept the new bullet without shaving the sides. This amount of expansion is only a few thousandths. Crimping is the last step where the bullet is seated and the diameter of the mouth is reduced in the crimping die by only a few thousandths. This serves two purposes. First, it assures that the overall diameter of the cartridge is below 0.379 inches so it goes into the chamber easily. Second it provides a grip of the case on the bullet so that it can't be moved under the recoil of the gun. This is important in high power cartridges because the recoil is quite strong. Remember Newton's first law. I did once not properly crimp some high power .44 magnums and I had bullets backing out of the case. Fortunately I caught it before they came out far enough to jam the cylinder.

Today's photo is a crimped (left) and uncrimped cartridge. You can easily see the amount of crimp is not very much, a few thousandths, but that is all that is needed. It is into a groove on the bullet called a cannelure.