I thought I had heard of a device for making aluminum gas checks but cannot find the article. I have heard quite a bit of chatter about using 40 S&W cases in 44's and 444's as jackets for bullets, and 380 cases for 375 jackets. From what I have generally heard here , and personal experience, if you use a harder alloy and good lube, you can get 2000 fps without checks. My question would be, what are you wanting to do that cannot be done by a good bullet at 1600 fps? The only things I can think of is long range varminting, and some competitive matches with specific requirements. Both hunting at short/ medium ranges, and practice and plinking, do not require premium bullets. I buy small bore match or varmint bullets , the cast are relegated to handguns and big bore rifles. Do you use gas checks on your everyday/ plinking ammo?