The 12 gage slug gun with the brass hulls was probably over 20 years ago. I found an old box of 12 gage brass hulls, and a old gunsmith friend had a 12 gauge rifled barrel. Built the thing on an old H&R singleshot frame. Cast slugs for it, cut the cases back to about 1/2 the original length. Didn't have a chrony back then, thing would rattle your teeth when you shot it, and I traded it off. I couldn't get it to shoot smaller than a foot or so at 50 yards, but most of that could have been me dreading to pull the trigger. The 17/454 took 11 dies to get from 454 to 17, you could do it in less dies, but would lose cases. It also didn't give enough more velocity to make it worth the effort. You reach a point with the 17's that once you pass 4000 fps, increasing case capacity doesn't give that much more velocity. The barrel I was using didn't have a fast enough twist to use more than a 30 grain bullet. The 17 Jet would do almost the same velocity with a smaller case and less powder. Bigger is not always better in factory or wildcats. The older I get the easier it is to be satisfied with a little less velocity, and longer barrel life. Dead is dead when I shoot critters, how far you can scatter the little body parts isn't a big deal now. I was told as a kid, "You can't build just one wildcat." The older I get the more I agree. You build what you want to build because "It is yours", no other reason is needed. That is the wonderful thing about them, and the reason I'll be building something till I die. Some of the ones that have been the most fun were someone elses brain child that hadn't been done. The 17 short is a good example of that. It goes back to not why, but why not? Nothing like owning and shooting something you can't buy.