I worked up a nice load for my 45-70 using bullets from an Accurate 460-415V mold. I had ordered a sample pack of 45 caliber gas checks from Vulcan. The copper ones fit beautifully, and I got a load that shot 1.2" @100 yds. So I need to make more for hunting season. I went to their site, and no copper. I emailed them and got a reply that said they had to pull the copper ones due to some manufacturing problems. Now what? I am assuming that checks from a different company would be slightly different. Or wouldn't they? They still have aluminum but they didn't fit as nicely as aluminum. If I remember the copper was a bit thicker. Here's the kicker. Season opens in 2 weeks so I really don't have a lot of time to try a lot of different things!