noob question about crimping.

Discussion in 'The Ammo & Reloading Forum' started by Big Chevy, Mar 11, 2012.

  1. Big Chevy

    Big Chevy Member

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    I'm just starting out loading .40, .45 and .38/357, FMJ, I'm using RCBS carbide die sets. My question is how can u tell if you have to much crimp, and how do you measure a crimp? Should the case width be the same throughout? Is it the same crimp for the cannelure ring on the .38/.357? Any help would be appreciated!
  2. garydude

    garydude Member

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    Check out this thread by our esteemed LDBennet on crimping. Any other questions that he didn't address, please let us know. Lots of help available to you here.
  3. garydude

    garydude Member

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    Oh, and welcome to the forum! :dance::dance::dance:
  4. woolleyworm

    woolleyworm Active Member

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    Welcome BigChevy ! 40 & 45 headspace off the mouth; so you are applying a taper crimp which i like to refer to as more of a squeeze than a crimp. You are just taking off the expansion applied by the expanded die before seating the bullet. You use calipers to measure your final dimension at the bullet case mouth and then make sure youre within SAMMI spec.

    The 38/357 gets a roll crimp which will "roll" the case mouth into the crimp groove of the bullet. You can also use calipers to measure. There is no set spec: just make sure that the bullet will not set back into the case; i push it against the side of my bench. Also with a new load; ENSURE that you check the rounds in your cylinder after each shot for the first couple cylinders. Heavier loads typically require heavier crimp. H110 is a powder that like heavy crimp to burn well; usually used for heavy mag loads.
  5. JLA

    JLA Well-Known Member

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    The .40 and .45 (im assuming ACP) are both auto cartridges and headspace on the casemouth. They will need very little taper crimp. Just enough to bell the casemouth. You measure the amount of taper crimp by measuring the diameter of the cartridge at the mouth. for .45ACP is should be about .470" give or take .001". and the .40 should measure about .419", again, give or take .001"

    The .38/.357 revolver cartridge like all other revolver cartridges will use a roll crimp. The cartridge headspaces on the cartridge rim so the amount of crimp isnt as crucial to cartridge performance. So long as they are crimped in there good enough to keep the bullets still under recoil youre golden. The best way to measure the amount of roll crimp in my opinion is to just use a tight crimp on all revolver rounds. You get a maximum crimp by turning the seating plug out and adjusting the die body down a little at a time to increase the amount of crimp. go until the case bears a slight bright ring at the casemouth. This indicates the die is applying a maximum crimp and is just starting to dig into the casemouth a bit, then back it of a smidge and set the lock ring and turn your seating plug back down on the crimped round to regain your seating depth.
  6. JLA

    JLA Well-Known Member

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    Dangit worm your fingers are faster than mine. ;)
  7. Big Chevy

    Big Chevy Member

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    Thanks everyone for welcoming me to the forum,worm & JLA just the answers I was looking for thanks a lot!!
  8. Hawg

    Hawg Active Member

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    Or get a factory crimp die.:D
  9. JLA

    JLA Well-Known Member

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    Even still the LFCDs apply the same types of crimp and they are set, adjusted, and measured the same way.
  10. LDBennett

    LDBennett Active Member

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    A couple of things:

    Don't over crimp. If the diameter of the case just below the crimp is larger than the area below that then the excessive crimp bowed the case out. It can be so severe that the case will not fit the gun's chamber. Enough is enough and too much is bad. Measuring the crimp and matching it to the specs in the reloading manual (SAMMI specs) is the correct way.

    The LEE Factory Crimp Die for Bottle necked rifle cartridges works completely differently than the LEE Factory Crimp Die for straight walled pistol rounds. The former is inventive and the later is a problem solver for Glock owners whose chamber tend to ballon the fired cases near the rim.

    The bottle neck case version (most rifle cartridges) works on a collet principal where the case neck is squeezed down on the bullet rather than folded into the bullet. The straight walled version (most pistol cartridges) crimps just likes any other seating die (taper for semi-auto and roll for revolvers) but includes a carbon ring in the mouth of the die that sizes the area of the case that a regular sizing die normally misses. I like the rifle version and since I don't own a Glock don't care for the pistol version (all my semi-auto pistols have well supported chambers).

    LDBennett
  11. JLA

    JLA Well-Known Member

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    Not exactly true regarding the LFCD for pistol and revolver LD. The Carbide post sizer ring sizes the same amount of the case the FL die does, it just does it after the bullet is seated and crimped in place to ensure the cartridge functions in ALL chambers for that cartridge. Glock bulge still has to be swaged out with a bulgebuster. Which incidentally uses the LFCD for that cartridge with the crimp plug and stem removed so the cases may be pushed completely thru the dies carbide sizer, very much like sizing a cast bullet. Thats the ONLY way to remove glock bulge.
  12. LDBennett

    LDBennett Active Member

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    JLA:

    OK, but the fact remains that the LEE Factory crimp die is different between the rifle (bottleneck case ) version and the pistol (straight wall case) version. That was my point even though I got the reason for the LFCD pistol version a bit wrong. The real use of the pistol LFCD is when the bullets are over crimped and the case bulges (right??) which leads me to believe there is no need for the LFCD for pistols, unless you are sloppy in your crimping. I think the rifle version is great. It is the only LEE tool that I actively support. Along with this I think that excessive crimping is over rated. Modern die sets have more neck tension built in.The expander button is, in most cases, now smaller in diameter than in years past to get more neck tension and in my mind relieving the crimp of some of its duties to hold the bullet in place during firing and in its recoil ride in a magazine or in an adjacent cylinder chamber of a revolver.

    Thanks for the clarifications.

    LDBennett
  13. JLA

    JLA Well-Known Member

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    For the most part I can agree LD. ;)

    Lee Rules!
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