So, I’m continuing on in my pursuit of crafting some 2.5” shot shells for my 1926 sxs double barrel with 2.5” chambers. 

My BPI trimmer trims the 2.75” hulls to just shy of 2.5”, 2-7/16”, so size wise, it’s safe. Then, I load the components per the manual based on 2.75” shot shell data, and add a roll crimp with my antique roll crimping tool. 

Before I was just cutting open factory shot shells, trimming it off to 2.5”, sticking everything back in and roll crimp, seemed to work. But these brand new Cheddite hulls trimmed to 2.5” seem to have a much larger gap between the shot and the overshot cards. So I tried adding 4-5 overshot cards (you can see a couple of my shells have a few) and still no dice (the overshot cards are just hole punched shotshell box cardboard). I tried adding a heavy roll crimp and it simply mangled the case mouth (shell #3 in the first picture). Do I just need a larger overshot card, or a filler wad like cork? Will that raise the pressure too much using a larger overshot card or cork? Will these rounds be safe to fire as a test in their current state (the overshot card actually holds it in place despite the gap as well)?

Thanks for your input and guidance from the community!

SHOTSHELL HELP! Roll crimps not reaching overshot card. Even with more overshot cards it still doesn’t reach. 2.5” shot shells for reference.