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Old February 18, 2013, 01:40 AM   #20
david_r
Senior Member
 
Join Date: January 9, 2013
Posts: 131
The maximum COL for a 9mm is 1.169. If you have a different number, it is not a maximum COL. Manuals list either minimum COL or as tested COL in my experience. Since pressure increases as case volume decreases, you would be best served treating the published COL as the absolute minimum length. Increasing the length while still being able to load the magazines and chamber the rounds is generally considered safe.

Someone with a Speer manual can provide more details of this which has been often quoted "Speer deliberately seated .030" deeper than a SAAMI tested OAL, and pressures went from 28,000 to 62,000"

If it is an optical illusion in your picture and you aren't crimping on the ogive, then just stay above minimum COL for that load data. If you are on the ogive, seat the bullets longer until you are able to crimp on the maximum diameter of the bullet. Then drop them into your chamber to make sure they chamber. (plunk test)

One thing that confuses people is the name of the die. It should be called a de-belling die. With a case that headspaces on the mouth 9mm, 40SW, 45ACP, etc, you are not crimping into a cannelure. You are only smoothing out the bell you created to ease the bullet into the case. Run your fingernail over a factory round and you can see that the full thickness of the case is still there and not buried in the side of the bullet. You need that lip there to stop the case from going too far into the chamber. If you pull your bullets, you will see that there is a ring in the jacket from the mouth of the case.

Once you get your crimp sorted out, you may take care of the ring in the bullets at the same time. It should also take care of the firing pin drag marks on your primers.

If you do decide to pull those bullets, re-size your brass again.

Good luck
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