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Old January 12, 2001, 03:30 PM   #1
SharpCdn
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I've been reloading for a couple years now, but I always end up in the same boat when it comes to crimping. Right now all I reload is 38/357. I am using a dillon 650. I like to experiment with different bullet types/weights a lot. However, I never know if the crimp I am putting on the bullet is identical to the last time I had set up for that same bullet.

I am wondering if there is a known method for obtaining a consistent crimp after changing your dies back and forth for various types of bullets/calibres.

Is there a way to quantify an amount of crimp pressure?
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Old January 12, 2001, 05:31 PM   #2
Bud Helms
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You could measure from the top of the die to the top of the tool holder and adjust it to a premeasured height.
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Old January 12, 2001, 09:45 PM   #3
char923
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On my 550 I use two sets of die, each on it's own tool head, one setup for 38 special and the other setup for .357 Mag. That the nice thing about Dillon press after you get your die setup you dont have to mess with them, just swap tool heads and powder measure.
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Old January 12, 2001, 10:38 PM   #4
ViKing
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I use a RockThrower single stage press, and this works for me:

The cases have to be trimmed to the same length. Back out your crimp a turn or so. Put a case in the press (what do you call a shell holder in a progressive?) and crank the ram to the top. Now screw down the crimp die until it just touches the case. This is the 'zero crimp' setting. Remove the case, and screw down the die an exact amount. Most dies have hex nuts for adjustment in the press, so I keep a record of how many 1/2 flat of the hex nut I screw the die in, so there are 12 steps in a full turn. If the die body has no reference marks, make one with a file or stone. I only reload for revolvers, and use RCBS dies. I keep a note in my notebook as to how much crimp I use with what load. A '4' crimp would be 4 x 1/12 of a turn, or 2 flats on the nut, or 1/3 turn.

This is a lot simpler in practice than it is to explain.
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Old January 13, 2001, 09:43 AM   #5
SharpCdn
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Thanks guys for the responses so far.

Viking, that sounds like an excellent idea of how to keep the crimp amount consistent. Its too bad they don't make a crimping die that has an accurate scale on it, to assist in this process, but I will try that idea out for sure.
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Old January 15, 2001, 06:59 PM   #6
Poodleshooter
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I'm not sure if this is what you're looking for, but I used to use a caliper to measure diameter at the very top of the case (at the crimp). When this measure is taken in accord with the known case diameter, it should give a consistant measure of applied crimp if the case walls are of a consistent thickness.
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Old January 15, 2001, 07:05 PM   #7
SharpCdn
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Poodleshooter,

Thanks for the response.

How do you accurately measure the mouth opening when it is a rolled/curved surface though?

Unless you were talking about a taper or profile crimp, in which case that makes perfect sense to me.

If you are talking about a rolled crimp, do you have a special technique for getting this measurement?

Just curious.
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Old January 18, 2001, 02:33 PM   #8
griz
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Sorry for the late posting but I was away for the weekend. I like to leave the die set so it crimps the same each time. If you want to switch between 38 and 357 you can still preserve the setting by using a washer that is the same thickness as the difference in length between the two cases. I made mine but one of the die manufacturers sells one (RCBS?) I haven’t tried measuring the crimp but you can judge them fairly well just by appearance. As mentioned before, compare yours to factory rounds. Look at a couple different brands as the crimp varies even between factory loads. The only problem I have had with the "set it and leave it" method is some jacketed bullets have a very shallow crimping cannalure (SP?) and the deep crimp I like to use for lead bullets does not work well with these.
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Old January 18, 2001, 03:11 PM   #9
Norm Lee
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Set the crimp

Hey Canuck:

Lots of good ideas here. A simple thing to do is to save a reference round for each of the bullet types you shoot. Then when you are ready to load that type again, back off the crimp die, place sample round in shell plate, lower handle (raise ram), spin crimp die down to contact, lock in. Good to go
Cheers,

Norm
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Old January 18, 2001, 04:38 PM   #10
SharpCdn
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Hey Norm Lee,

That sounds incredibly simple, and I'll bet it works. From now on I'll keep reference samples for each load. Thanks for the idea.

Actually all the advice has been great, thanks to all who responded.
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Old January 18, 2001, 04:56 PM   #11
Poodleshooter
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Sorry, I usually only worry about taper crimps, as all of my roll crimped cartridges headspace on their rims! For roll crimps I just mark the die and always tighten it 1/4 turn (1/2 turn for slower magnum powders). The critical issue for roll crimps is the length. My belief is that if you trim (or measure) and get consistent case length, you will get consistent crimp. I also eyeball the crimp compared to the bullet cannelure. You'd be surprised how well you can compare crimps that way.
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