9mm crimp

[RobZ71LM7]

Ok so after sizing, expanding, and seating I measure .376-.377. Most (online) seem to crimp to .377 or .378. Unless I expand my cases so much I run the risk of weakening them I'm not getting readings above .377, but there is still a slight bell. Typical or weird? My seater die is backed out so it's not crimping. I never loaded 9mm before-only .45 and then I crimped to .471 which agrees with most. I used two different Starret dial calipers and both agree with each other.

Winchester brass, Berry 9mm 124 gr FMJ.

 

[rfwobbly]

Rob -

On a 9x19, you should be using a separate taper crimp die, or doing the taper crimp in the seating die. If you're getting .377 dia on the very tip of the case mouth, then you're getting good results. It doesn't matter so much what it looks like, but rather does it freely drop into your chamber under it's own weight ?? That's the true test.

Generally, .377-.378 is considered in the good-to-go range. You don't want more than that or you'll get into trouble with plated bullets. Also, going more than that can bury the case mouth and make it hard for the case to head space on the end of the chamber.

9mm crimp dia can be difficult to measure due to the extreme taper of the case, so go slow.