The 44 cal copper gas checks are an easy fit on cast bullets for the 404, no real need for custom gas checks.

For some stupid reason that has always escaped me, I had a bullet mould made by Richard Hoch 36 years ago to cast a plain base 400gr bullet for my 404 (the stupid part being the plain base, the Hoch mould itself is a work of art) but I have devised a simple method of quickly turning a shoulder on the bullet base to take a 44 cal gas check and the bullets size perfectly in my Lyman 450 lube/sizer.

The photo below shows my own cast bullet on the right and another NE members 404 bullet on the left, both with standard 44 cal gas checks sized in place.