I wanted to try a new 9mm bullet for IDPA, so I picked up a Lyman 4 cavity 356637. It's supposed to cast a 147 grain bullet, but with my alloy it comes out at about 154 grains. I cast a bunch of good looking bullets and went to my Lyman Pistol and Revolver Reloading Handbook to find a load that would meet my requirments.
For IDPA I need a power factor of 125,000, so that means that I need a velocity of at least 812 ft/sec. with this bullet. The reloading manual says 1.9 grains of Clays gives 669 ft/sec, and the max load of 2.8 grains gives 873 ft/sec. So I figured I would start with 2.5 grains and see how that worked.
I loaded up about 20 rounds (2.5 grains, 1.058 OAL) and headed to the range. I shot off the first couple, and the load felt good, and they hit the target pretty close to the point of aim (I wasn't really trying at this point) So I loaded a magazine with 5 and let them go down range....well not all of them. The gun (Colt Combat Commander) jammed after four rounds. I couldn't move the slide. Then I noticed some of my brass on the floor. The cases had no primers. I found some primers on the floor, and they were flat as a pancake, and mushroomed a bit. The brass had a clear line indicating the portion that wasn't supported, but wasn't fractured as far as I could tell.
When I got home, I was able to get the gun apart and found a piece of brass wedged between the barrel and slide, and no damage to the gun. Anyway, close call for me and the gun. Yes, I know I should have started with the starting load. Valuable lesson learned. I just never had a problem before with a mid-range load from a loading manual. I think I'll try a slower more dense powder next, and start with the starting load.
Long Story, but I thought it was worth telling
