9mm bullets unseat in revolver

[jcc7x7]

52 minutes ago, MWP said:

Star line worked fine for when it was new for me, it was after that initial loading I had issues. Have you only fired the brass once so far or multiple times?

I had the same issues

Even when I called Starline they suggested to use some one else's brass FWIW

[MikeyScuba]

[PatJones]

Properly adjusted, a taper crimp die simply takes the bell out of the case mouth to make the case feed properly. A taper crimp does not hold the bullet in, it cannot.

Brass springs back just a little bit after forming, that's why it works so well as a case. After firing, brass springs back from the chamber wall making it easier to extract. Lead is a dead metal and does not spring back after forming. If you crimp the case mouth in too far it will deform the lead, making the bullet smaller, and the case will spring back just a little bit. This can actually loosen the tension on the bullet.

In a 9mm case, the bullet is retained by neck tension. The inside of the case mouth is a little smaller than the bullet diameter and this tension holds the bullet in place. I find some of the plated bullets are undersized and therefore have less tension holding them in place.

Before moving to a roll crimp, I would try one of the undersized resizing dies sold by EGW. This would increase the neck tension that holds the bullet in place by sizing the case down a little smaller.
https://www.egwguns.com/smithing-tooling/undersize-reloading-dies/

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[rwagner24]

Yep I understand. I ordered that exact resizing die yesterday also. 

[rwagner24]

Got my Lee undersized die today. Went a little shorter on my original OAL so there was more bullet in the case. Can definitely see it grabs the bullet tighter but it still moved. Started with 1.140 shot 7 shots took last out measures 1.147 already. I also got my .38 short roll crimp die. I’m just going to wait on my other bullets that have the groove for the roll crimp.