acropora
Member
Mostly it stems from the shape of the round. Because the rounds have the large rim on the back, getting them to stack properly and feed reliably is an issue.
The size of the rounds is a small issue, but mainly from the standpoint of the size of everything else. If you are working with a 120mm self loading gun you can have slightly wider tolerances because overall it is a very small % of change. If you add a millimeter for space no one will notice. Add a millimeter for a .22 and it's almost 1/4 the diameter of the round! Like adding 30cm to the 120mm!
KBK
that makes it easy to understand,thanks for the answer.