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Discussion Starter #1
The SAAMI drawing shows the 9mm case to be 0.380" diameter at the mouth. When my cases come out of the sizing die they are .372" diameter. I expand to .378 - .380 and lead or jacketed bullets seat without a problem. After crimping they are .375 - .376" dia. at the mouth.

I tried to adjust the size to get .380 after crimping, but the bullets were too loose and it was easy to set them back.

I'm not sure what to make of this difference. Is it a problem or is it normal?
 

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The SAAMI drawing shows the 9mm case to be 0.380" diameter at the mouth. When my cases come out of the sizing die they are .372" diameter. I expand to .378 - .380 and lead or jacketed bullets seat without a problem. After crimping they are .375 - .376" dia. at the mouth.

I tried to adjust the size to get .380 after crimping, but the bullets were too loose and it was easy to set them back.

I'm not sure what to make of this difference. Is it a problem or is it normal?
You're okay. Most sizing dies are a little tighter than SAAMI specs.
 

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Discussion Starter #4 (Edited)
OK, thanks for the replies. That brings up another question. Should the cartridges be crimped down to the size they were coming out of the sizing die i.e. .372" diameter? The rounds crimped to .376 seem pretty tight and I have not had any problems with failure to feed, fire, or eject.
 

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Aren't these reloading 101 questions that are answered in manuals?
Crimping, for cases that headspace on the case mouth, is done to remove any case mouth flare and to make the transition from bullet to case easier so you don't get failure-to-feed due to the case mouth catching on the ramp.
We old-timers learned to adjust crimp by FEELING the transition and being sure not to crimp any more than required. The young'uns now want to measure and be told what to do.
If your reloads feed fine, then your crimp is fine.
Be sure to check each cartridge for bullet set-back by pressing the bullet meplat against the bench and pushing the cartridge down with thumb pressure. Any movement is bad.
 
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