Having trouble sizing 10 gauge hulls

[Cory Rams]

I just bought four Alcan all brass hulls to use in my Charles Daly 2 7/8” 1873 SxS. I’m afraid I’ve wrecked them trying to get them to size. The shells are a hair longer than 2 7/8” but are way to swollen and don’t want to chamber. I’ve tried running them through a loose Mec sizing ring several times. I even polished the cases along the way. I trimmed one down a 1/16 shorter and got the breech to close but not without tinkering with it and doing so very firmly. I trimmed again closer to 2 5/8” and it’s about the same. A tight firm fit and the breech will close. I have to tap the hull out from the muzzle end with a cleaning rod. I’ve ran the hulls through my loose Mec sizer a good dozen times. The sizer ring is no connected to a Mec press so I’m Taping them in and out of the sizing ring using a socket. I do have some wrinkles on the shells where the ring must have came off unevenly. I’m wondering if I just keep cutting down the shells till they fit loosely? The gun was measured at 2 7/8” and I’ve shot RST 2 7/8” shells out of it with no issues of fitment or sticking. The RST and my reloads in plastic hulls drop in and out loosely. The used all brass Alcan shells I was told we’re used in a 10 gauge cannon so I wonder if the the chamber was extremely large compared to my gun? It seems that every time I run the shells through my Max sizing ring they seem to slde into both chambers a little easier. Just don’t want to run them up and down dozens of times till they fit properly. Any suggestions or did I get some hulls that I shouldn’t be using? My plan was to cut them all to match the other 2 5/8” and shoot them all to see if the hulls will fireform the wrinkled dents and hoping they would all fireform to the point the gulls might fit better? If not I’ll stick with plastic hulls.