300blk reloading question

[GriffonNorth]

So I have reloaded allot of other ammo in the past and bought a nice little 300blk which I think is a loads of fun to shoot but with the rona being a pain in the butt ;ammo in my neck of the woods has been scarce it seems some is coming around now but I already had a ton of 30cal bullets from 308, 06 and 300mag laying around why not reload 300blk. So I saved a bunch of different quality brand name hunting brass from Winchester, Hornady, and Federal and then proceeded to cut down a couple hundred LC 223 brass of the tons I have laying around to make some 300blk brass as well. Well when I went to go hand prime the commercial 300blk in my hand priming tool with a brand new rcbs #10 shell holder it didn't work basically at all. Grab the cut off 223 brass and they all primed like a champ. So I got to looking at the 300blk brass and noticed the space from the rim to the circular groove past the angle was actually abit bigger then 223 causing the case to be sloppy in the shell holder. Is there a special shell holder I am not aware of or can't find with normal research online. Cause I can't believe 3 different manufacturers are accidently making them this way. I also tried them in a brand new Lee shell holder and sloppy as you can get. I will try to add a pic to show you all. The two on the left are 223LC brass and the two on the right one was hornady and the other FC can't really tell the difference.