Question on lee factory crimp die.

[thefish]

I just loaded up about 400 rounds of 9mm today.
3.7 grains of tight group under a 124 grain xtreme coppetplated round nose. 1.135" oal.

I very slightly used the expander die, and my crimp diameter is .375 for the most part. The bullets had to be held in place as they were being seated, but no copper was shaved at all upon seating so I think that's pretty perfect.

My question is, with this crimp diameter, is running the bullets through the lee factory crimp die necessary?

And second question, how much variation in the crimp diameter is accecptable? What is the min/max crimp diameter?

Thanks in advance.

 

[Rule3]

No you do not need to use it. If you set your seating die to slight crimp it will smooth out whatever bell you put in the case. You say you didn't put much so you should be fine, The Seating die also crimps if you want it to,

 

[mljdeckard]

I don't worry about actual crimp diameter as much as my plunk test. I use one Lee FCD because it has the post sizing rings, not because I want a better crimp. Most modern guns have a little bit of slop in the chamber, there's (literally) some wiggle room for crimp standards.

 

[Walkalong]

The "crimp" on 9MM should remove the bell or maybe .001 more. Skip the FCD and buy a crimp only die. The Lee is about $12. Or just "crimp" with the seater.

http://www.thehighroad.org/showpost.php?p=7699828&postcount=14

http://www.thehighroad.org/showpost.php?p=7713612&postcount=10

 

[LiveLife]

And second question, how much variation in the crimp diameter is accecptable? What is the min/max crimp diameter?

With plated bullets, you do not want to use too much taper crimp or you may start to cut into the copper plating at .375" and may experience decreased accuracy.

With an average case wall thickness of .012", you want to use no less than .377" - .378" taper crimp (.355" + .012" + .012" = .379") with a max of .380".


As to FCD, as many posted, as long as finished rounds feed/chamber reliably, no need for FCD, just taper crimp die or combination bullet seating/taper crimp die.

 

[kcofohio]

I agree with light crimping of the plated bullets. My first loads were with 115 gr. Berry's, and had the crimp set to heavy. When I pulled the first set of bullets, the diameter on a few of the bullets were around .352" and some showed signs of tearing the plating.

 

[wlkjr]

I'm using 3.6 gr. TG with 124 Xtreme HP in a Glock. Like the others said, just a very light crimp. I'm using a Dillon 650 and seperate crimp die.

 

[Walkalong]

I agree with light crimping of the plated bullets

The "crimp" on 9MM should be just enough to remove the bell or a hair more, no matter what bullet it is, lead, plated, or jacketed.

 

[thefish]

Awesome. Thanks guys.