Lee crimp die shim

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Lee crimp die shim

Postby Jp14495 » Fri Oct 21, 2016 3:30 pm

So I've been snooping around here a bit and doing quite a bit of reading and watching the videos. I'm getting ready to start reloading the bushmaster and have been getting all the stuff together to do it. As a side note i've been reloading 20+ years and dont use any factory ammo in any of my own 15+ guns, well except .22's lol.

Anyway my question on the lee side crimp die. Where did you guys come up with cutting off a half inch? And then why use shims? I get it to be able to put severial crimps on one case but does anyone do this? Why do this extra step? I work as a manual machinist so cutting the die down is no big deal. I plan on cutting it down the difference in length of the 45-70 to that of the 450b. So it puts the crimp at the neck just like it would have done on the 45-70. Any reason not too?? Am i missing something?
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Re: Lee crimp die shim

Postby Hoot » Mon Oct 24, 2016 5:13 am

Welcome aboard JP.

Being able to make multiple crimps on a cartridge is one reason for the shims, but not the compelling reason. To me, the biggest reason is for when the cannelure or driving band groove is in different positions once you have the bullet seated to the depth that yields the best accuracy for your rifle. They are rarely located in the same place from one bullet brand, model or weight, to the next. I like to hit my desired crimp at the maximum height of the ram, so that I an produce the crimp with consistency from one cartridge to the next. Since the die height directly affects the crimp depth, there is a narrow sweet zone that you can adjust it to so that it engages at the top of the ram stroke. The shims allow you to move that sweet zone plus or minus. Think of it as a double variable equation. Change one and it impacts the other.You almost have to experience it in action to appreciate what I'm saying. That's how I first discovered the need for the shims. Kinda like "Wait... now that's not right anymore! Damn!" :evil:

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Re: Lee crimp die shim

Postby Jp14495 » Mon Oct 24, 2016 12:10 pm

I got you, thanks for the info. I have played with it some since i posted this question. Now i understand. I use a multi stage press and shims make to much hassle for me. I just decided that at $15 i'll just cut new dies for each bullet i use. Or maybe just new guts and pop them in and out as i need different lengths. Thanks for the help!
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Re: Lee crimp die shim

Postby Al in Mi » Mon Oct 24, 2016 12:54 pm

Jp14495 wrote:So I've been snooping around here a bit and doing quite a bit of reading and watching the videos. I'm getting ready to start reloading the bushmaster and have been getting all the stuff together to do it. As a side note i've been reloading 20+ years and dont use any factory ammo in any of my own 15+ guns, well except .22's lol.

Anyway my question on the lee side crimp die. Where did you guys come up with cutting off a half inch? And then why use shims? I get it to be able to put severial crimps on one case but does anyone do this? Why do this extra step? I work as a manual machinist so cutting the die down is no big deal. I plan on cutting it down the difference in length of the 45-70 to that of the 450b. So it puts the crimp at the neck just like it would have done on the 45-70. Any reason not too?? Am i missing something?



the 450 headspaces off the case mouth, if your planning on crimping in a cannuler with a Lee die, you could get miss fires, at least I did
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Re: Lee crimp die shim

Postby Jp14495 » Mon Oct 24, 2016 3:36 pm

Good to know thanks, was planning on doing two crimps the hornady die set crimp anf the lee crimp. Might not need the lee crimp, guess ill see what happens with my loads.
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Re: Lee crimp die shim

Postby Jim in Houston » Sat Oct 29, 2016 12:08 pm

Jp14495 wrote:Good to know thanks, was planning on doing two crimps the hornady die set crimp anf the lee crimp. Might not need the lee crimp, guess ill see what happens with my loads.


No, you don't need the Lee (side) crimp. Just go with the taper crimp produced by the Hornady crimping die to start. The Lee crimp may give some additional performance, if done to the right depth and in the right location, which can vary from bullet to bullet, but it tends to complicate the reloading process at first.

If you do use the Lee die, taper crimp afterwards to remove any "belling" on the case mouth caused by the side crimp.
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