No.Is it necessary to have the factory crimp die?
No.Has anyone used a Lee Autodrum powder measure with RCBS dies? Can that work?
Pretty clear that you’re confusing the finished measurements of the round with the tools needed to achieve that result.But they aren't the same ... or, if they are, they shouldn't be.
Per SAAMI, .380 ACP should have a case OD of .3730 at the mouth, and .3731 at .04" back from the mouth. 9mm should have an OD of .3800 at the mouth and .3811 at .04 back from the mouth. That difference of .007 could mean the difference between chambering properly, or not chambering properly.