I have a 20 practical that I have to small base for. I don't like it because it means two passes one in a redding bushing die, and one in an RCBS small base die. Its the first one I have ran into that stuck cases without a small base die. Its really bad with brass from a "5.56 match" chamber I have. I didn't even think about it making some ammo to break in the AR, lucky with the decapping pin out of the RCBS X die, I was able to small base size the ammo rather pulling it all down.Ok, so I went and took pictures of my brass in different stages just at the web. Trying to measure the body consistently was a joke.
First picture is fired brass out of my old chamber. .471”
Second picture is fired brass from new chamber. .469”
Third is brass from old chamber run through my Redding type 2 full length sizing die. .470
Fourth is that exact same brass that was sized with the Redding now run through the rcbs small base die. .467”
And yes, I am aware that calipers are not as accurate as micrometers or what ever other tool that’s better but it’s enough to show the difference.
And best I could do for pictures but the shell holder and die are 100% in contact.
I really do appreciate everyone’s help with this. Just trying to provide some more data for future people that might search this.