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  #1  
Old 02-03-2017, 11:58 AM
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Crimping .357


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The final operation loading my .357 Magnum is the seat and crimp. I have read the .357 needs a good crimp. After trying to seat and crimp in one operation, with a good crimp I crushed the brass. I have now decided to make this in two steps. What I need to know is the definition of "good". I compare my crimp to commercial rounds and say, that looks pretty good. I bow to the more experienced, what can you tell me about the crimp. Hopefully I am not making this more complicated than it is.
Thanks from Western Wisconsin.
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  #2  
Old 02-03-2017, 12:46 PM
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Iowaloha. You just discovered "how far is too far". Just learn to "feel it". A related discussion can be found here. https://www.shootersforum.com/handlo...se-length.html
Or find your own way around.

Cheezywan
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  #3  
Old 02-03-2017, 03:29 PM
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I seat and crimp in two steps to better control the crimp. It works for me. A "good" crimp is rather subjective. I crimp magnum round so the top extends into the cannelure in good fashion. There are many pictures out there. Look at some on the forums and try crimping a little at a time until it looks good. You don't have to overdue it. For me, If i see a distinct band at the top of the brass in the cannelure then I've crimped too much.
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  #4  
Old 02-03-2017, 03:50 PM
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The key to crimping whether you're seating in the same step is to make sure the brass is all trimmed too the same lengths. Other wise the crimp will be heavier on some and lighter on others. Also problematic with inconsistent brass lengths is the crimp may be into the canelure on some, while others it may crimp outside of the canelure, thus causing crushed cases.

As for how much crimp is enough, this is a process of adjusting the die until you aren't crushing brass.

SMOA
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  #5  
Old 02-03-2017, 05:59 PM
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Quote:
Originally Posted by Submoa View Post
The key to crimping whether you're seating in the same step is to make sure the brass is all trimmed too the same lengths.
Uniform length is essential, especially with jacketed bullets.

Cast or swaged lead, the lead takes a beating. Jacketed bullets, the case takes the hit.
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Old 02-05-2017, 09:12 PM
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I've always used one step, and have never trimmed the brass, but two steps is a good idea until you are more experienced. A "good" crimp for .357 is when the bullets don't creep by the time you fire the 6th shot from your revolver. If you are shooting from a carbine, you can get by with considerably less of one.
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  #7  
Old 02-06-2017, 06:38 AM
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I always use a 2 step process as well. Seating, then crimping. For the crimping phase, I find the Lee Factory Crimp Die works very well for me, at least. You can easily adjust the amount of crimp you want to apply.

And here's my official, detailed and specific crimp dimensions for 357 - just make it a "stiff" crimp. Works very well with magnum powders!

Bayou
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  #8  
Old 02-06-2017, 10:40 AM
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For a new reloader, comparing your crimp to factory ammo crimps is prolly the easiest. For your .357 you could do the "shoot and see" test (load 6 in your revolver, shoot five, measure OAL of the unfired 6th round. If it grows, add a bit more crimp, just not so much the case gets buckled).
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Old 02-06-2017, 12:10 PM
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Having a good magnifying glass helps a lot when you are trying to work how much crimp you have.
I use one i made from a scope by using both ends put together , bit of over kill but it is good and makes all the difference to be able to see what's going on.
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  #10  
Old 02-06-2017, 05:25 PM
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If you can catch a fingernail on the brass the crimp is light.
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  #11  
Old 02-07-2017, 04:27 AM
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Take a look at the Lee Collet crimp die. They make one for 357 Magnum.

I like the crimp groove on Elmer Keith's bullets.
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  #12  
Old 02-07-2017, 05:34 AM
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I reload .357 magnum using cast lead bullets with a crimp groove mainly to punch paper. I seat and crimp in one operation. All cases are trimmed to 0.005" longer than the specified trim-to length. Consistent case lengths are key to good crimps. My crimps duplicate factory and the case mouth is even with the top of the crimp groove when done. If you see a band on the case mouth after crimping, that's a sign that the crimper in your seating die is set too far down and you're riding over the case mouth and crushing it. Factory crimps show little to no band at the case mouth.

If reloading with jacketed bullets, even less crimp is necessary as factory crimps will show the case mouth is imbedded into the bullet's crimp band but only about half-way. The crimp should definitely imbed into the striations in the crimp band but need not be to the bottom of the striations.

In all cases, bullets that are jumping their crimp without being fired indicates more crimp is needed and less crimp is needed if the crimp is leaving a band on or crushing the case mouth.

It takes a bit of adjusting to get the correct crimp and a lot of this is subjective. Let the factory crimps be your guide as to what your crimps should look like. Just my dos centavos, comments welcomed whether for or against.
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  #13  
Old 02-07-2017, 06:56 AM
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Quote:
Originally Posted by Marshal Kane View Post
It takes a bit of adjusting to get the correct crimp and a lot of this is subjective. Just my dos centavos, comments welcomed whether for or against.
It's often a discussion on any forum, but the crimp process is filled with "it depends".

I don't recall ever having any problems with my .44 Magnum loads, as even though recoil is pretty sharp, the guns I've used are fairly heavy, and/or I don't shoot heavy loads in my M69. But I have had bullets back out in my M637 using Remington brass, (thinner walls than most, and Hornady Cowboy bullets). The combination of graphite lube, light brass, and bullets at the minimum diameter, made a light crimp un-useable.

Between those two extremes, I can see there are no rules. You have to understand the limitations of all the components, and be prepared to adapt.
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  #14  
Old 02-07-2017, 08:47 AM
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A separate Crimping die.

In my experience, I have found the easy way to do is to get a separate crimping die. This die can be a Lee or a Dillon or whatever. Overtime, it has paid off in terms of time-it's quick and easy to adjust. It's not necessary to make two adjustments in the same die. Only shooting lead bullets here, it is necessary to keep the lube from building up in the seating die(s). Keep in mind this is my experience. This is not intended to contradict anybody, Good luck on your loading. Stick with it.
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Last edited by William A. Reed; 02-07-2017 at 09:02 AM.
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  #15  
Old 02-13-2017, 03:59 PM
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Quote:
Originally Posted by Wrench Man View Post
If you can catch a fingernail on the brass the crimp is light.
and to add

I like Mike Venturino's description of a roll crimp
in Lyman's Cast Bullet Handbook (4th edition) page 61

"....run his fingernail down the bullet and over the case mouth. If it does not hang up on the case mouth there is enough crimp

Last edited by BillGlass; 02-13-2017 at 04:20 PM.
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  #16  
Old 02-19-2017, 05:52 PM
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I had a conversation with a rep from one of the major reloading die manufacturers recently, and he told me that factory crimps are overcrimps. That company's dies need to be adjusted so the crimping ring touches the case mouth, then, all you have is 1/4-1/2 turn of the die before running out of crimp, and developing the "belt" in the case mouth. I also use Mike Venturino's "fingernail test", to reduce hang ups in loading. Case length would be a definite factor in consistent crimps, and I find that a significant number of new cases, even from major manufacturers...Starline and Winchester, are shorter than minimum. Few are longer than necessary tho.
I an seriously looking for an "old style" seat/crimp die from one of the major manufacturers, which will put a heavy crimp, a'la the older Lyman manual illlustrations, which is what I learned from. Maybe the Lee Carbide Factory Crimp Die might be a solution?

Last edited by flyboy61; 02-19-2017 at 05:55 PM.
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  #17  
Old 02-25-2017, 02:35 PM
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"The key to crimping whether you're seating in the same step is to make sure the brass is all trimmed too the same lengths."

^^^^+1.

Mike knows more about shooting cast than about anyone ever will. His advice is very good and the picture in #15 is plenty of crimp.
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  #18  
Old 02-26-2017, 05:03 AM
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My seater dies are adjusted to give a crimp very similar to BillGlass' post #15. Brass "snuggles" right up to the front band and goes no further. Brass must all be of a consistent length in order to do this.

What I try to avoid:
Case being too long or seater plug set too deep causing the case mouth to "bite" into the front band and/or the crimper ring in the seater die riding over the case mouth leaving a bright band.

Case being too short or seater plug set too shallow leaving the case mouth with a gap to the front band.

Consistent crimps result in consistent bullet pulls and less variations in velocity. YMMV
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  #19  
Old 02-26-2017, 05:34 AM
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I keep all 357 cases trimmed at 1.280 and the dies stay locked down.
I use maybe 3 different 158 grain bullets, but they all crimp at the same.

Cases could be kept at 1.285" or whatever, as long as they are all at a consistent length and the dies adjusted to that length and then locked down.

To me, uniform means "the same"
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  #20  
Old 03-07-2017, 12:03 PM
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FWIW...Just to see, I did an experiment...I took some .357 brass, and measured them, then selected some of spec. length...1.280, some that measured ~.003 over, and some shorties that were ~.003 under. I set the crimp die for a "good" crimp, with "spec." length brass, with no fingernail catching, per Bill Glass' post, and loaded a bunch, then with the longer cases, and last, with the shorties. All achieved the "no fingernail catch" and they all fit with a satisfying "plunk" in my Dillon case gauge. So, when the cases get too long...if ever, I'll trim them, and go shooting. Any increase in accuracy that exact case length/crimp might realize will probably be totally eliminated by my shooting. Of course, at nearly 80, seeing the target is a challenge, some days! I'm going to keep my crimp die set right where it is, and use the machined washer (I have 2) that came with my the set to provide a no-crimp clearance when seating the bullets.

Update...Half of my latest purchase of Starline brass is shorter than the stated trim-to length in any reloading manual. I contacted them, and was told that they may turn out brass from 1.270-1.290, according to SAAMI rules. The 1.280 length published in the loading manuals since Lyman #3, iirc, is merely a "suggestion", sez he! Well! Thank you very much, Herr Customer Service Manager!

Sooo...That means either I modify my Lee Trimmer to shorten my ~1,000 .357 cases to a shorter length for consistency, or just keep throwing everything from Sheep to Shinola at my seat/ crimp die, and take what comes!

You wouldn't think that .003" shorter would make a practical difference in the world of us plinkers...or, am I just straining at gnats, here?
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Last edited by flyboy61; 03-16-2017 at 07:09 AM.
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