tgc
.30 Stingray
Posts: 142
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Post by tgc on Jan 2, 2014 19:50:47 GMT -5
Educate me a little.
I use roll crimps on my straight wall revolver loads. I understand it keeps the bullet in place under heavy recoil.
-What are the other benefits of roll crimping over say, no crimp at all? (if your bullets didn't move out and tie up the revolver) -Does the crimping improve accuracy of the load? Makes them more consistent I would think. -I've read sometimes about bla, bla load with a "good heavy crimp". What would be the difference with a "good light crimp"?
These are somethings about crimping I would like to know. Thanks. (this is not a roll crimp vs. taper crimp question)
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steve
.375 Atomic
Posts: 1,501
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Post by steve on Jan 2, 2014 21:25:03 GMT -5
A firm crimp plus neck tension helps "hold" the bullet a millisecond longer and allows slower powders to burn more uniformly. I'm sure someone here can give a better explanation, but that's how it was explained to me a long time ago.
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toddb
.240 Incinerator
Posts: 68
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Post by toddb on Jan 3, 2014 1:00:48 GMT -5
A firm crimp plus neck tension helps "hold" the bullet a millisecond longer and allows slower powders to burn more uniformly. I'm sure someone here can give a better explanation, but that's how it was explained to me a long time ago. I really cannot add much to the above statement in the technical arena. However, my 20+ years of reloading and revolver shooting has proven it to be a consistent fact. I shoot a lot of 2400, H110 4227 and even some slow rifle powders in larger (460 & 500 S&W loads with heavy projectiles) guns. The most consistent choreographed bullets and most accurate shooting I have ever experienced has been with slow powders in revolvers with firm crimp. Some specific combinations have been best with a very firm crimp. The 44 mag comes to mind with 2400..
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Post by bradshaw on Jan 3, 2014 7:03:00 GMT -5
tgc.... I crimp for the load. No more than necessary for reasons stated above. Neck tension is first criteria for consistent ignition. Obviously, a heavy load, and especially a heavy load in a light pistol, promotes pull and requires a hard crimp. A light target load with soft lead bullet is better with lease crimp possible.
Before any of that, I flare case mouth just enough to start bullet without biting. This prolongs case life.
I prefer a square case mouth to a heavily chamfered mouth. The square mouth bites better for a given crimp. David Bradshaw
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Post by tek4260 on Jan 3, 2014 7:11:48 GMT -5
To me, the primary purpose of a crimp is to prevent setback in an autoloader. Increased neck tension by modifying the expander plug in the flare die, or using a universal flare die, coupled with a bullet .001 larger than the throats made much more of a difference in my revolvers than any level of crimp did. A heavy crimp can destroy case neck tension by bulging the case below the crimp.
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tgc
.30 Stingray
Posts: 142
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Post by tgc on Jan 3, 2014 16:51:26 GMT -5
Thanks for the replys. This answers my questions about roll crimping.
But it leads to another question I have had, maybe start a new thread.
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Jan 4, 2014 12:34:22 GMT -5
One thing to watch on crimps, I have a number of 44 crimping dies, left over from past frustrations. I have noticed that while most dies crimp at an angle, my LEE die seems to crimp at a 90 degree angle no matter how light the crimp. In my mind, this is totally undesirable because that 90 degree crimp looks like it would be rough on case mouths, and also could possibly scrape the sides of the bullet as it leaves the case.
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Post by bradshaw on Jan 4, 2014 14:23:07 GMT -5
358156hp.... as you indicate, not all crimp dies are created equal. Some dies are abrupt or rough and don't make a proper crimp. These aberrations are not confined to a single maker. Similar dimensional flaws affect seating plugs. David Bradshaw
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