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Let's talk about crimp..

Discussion in 'Ammunition & Reloading' started by wavo, Jan 6, 2010.

  1. wavo

    wavo Portland Member

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    I have pretty much everything I need to reload except for one crucial element, bullets. Turns out those are mighty important in the reloading process. I have a bunch on order but they’re not here yet. I was in the mood to setup all my dies last night and I realized I would need a loose bullet in order to do execute the bullet seating and crimp step. I don’t know if it is advised or not, but I took my bullet puller and decided to pull some factory rounds and previous reloads I had lying around, just so I could get my die setup. This is where I ran into some interesting variances using the hammer-type inertia bullet puller.

    I stuck in an old reloaded round and was able to get the bullet out after about 2 or 3 whacks. After the bullet fell out I realized it was 124gr and I wanted to setup my die for 115gr (didn’t know if it made a difference or not, but wanted to be consistent). I grabbed a PMC 115gr and proceeded to whack the **** out of the round but could not get the bullet loose! The girlfriend wanted to have a go, but her muscular arms couldn’t get it to budge. After about 15 or 20 whacks I gave up and tried a Remington 115gr round. After three whacks the Remington bullet came out. Then I grabbed one of the handloads I made at John’s reloading class a couple weeks ago and after only ONE strong whack the bullet came out.

    Maybe this isn’t a big deal but this seemed quite a difference between the manufacturers! My question is how does one know when they have enough crimp? I’ve seen pictures of too much crimp where you can actually see the casing almost turning inward towards the bullet, but I think I’m more concerned on the low end. I positioned one of the loose bullets in my expanded casing and sent it up to the bullet seat/crimp die and it felt like barely anything happened (as far as resistance on the handle). When I dropped it down and measured, the OAL was fairly close to where it needed to be (haven’t had a chance to dial it in yet, but will). In the class I took, one way we were shown to ‘test’ if the crimp is strong enough is to drop it in the magazine and slam the slide forward loading the round. After a couple of times check the length with calipers and see if it has moved at all. I did this with my Beretta and after 3 slams it had moved +.02”.

    Is this ok/acceptable for crimp? Should I put more? I understand too much crimp is dangerous because of pressures and such, but is too little of crimp dangerous as well?
     
  2. deadeye

    deadeye Albany,OR. Moderator Staff Member

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    Too little of crimp could cause the bullet to seat further due to jostling while in mag or while stored if moved alot. Any actions causing loaded rounds to be vibrated or such could cause the bullet to sink into the case and create higher pressures if not crimped enough. The best way to reduce the roll of a crimp is to use factory crimp dies which sqeeze the neck rather than wedge it like most seating dies. You can over crimp with the factory crimp dies but it is noticeable as it will leave 4 striations around the neck.
     
  3. JohnH

    JohnH Milwaukie Active Member

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    For 9MM you won't feel much resistance when crimping compared to a larger case. Set your OAL length and continue to adjust your crimp until you can chamber and rechamber several times with no real noticeable changes in dimension.

    It doen't take that much to hold a bullet in place for a 9MM.
    Larger 44 Magnum revolvers and such are a lot different.

    Here is a little info:
    From the RCBS web site:
    Q. What is the difference between a roll crimp and a taper crimp?
    A. With a roll crimp the seater die actually rolls a very small portion of the case mouth into the bullet cannelure. If the seater die is set too low or the bullet does not have a cannelure, the die will attempt to form the crimp. However, it may turn too much of the case mouth in, or eliminate space to roll the neck into, which will distort or crush the case. The taper crimp die actually squeezes the case around the bullet. There should not be any indentation or other indication of a visible crimp. The die merely removes the bell from the case mouth that was used to ease seating of the bullet and pushes the case mouth parallel to the bullet. Anymore than that and the die begins to push down on the case wall and causes a bulge, preventing it from chambering.

    Information and a diagram showing ‘taper crimp’
    http://forum.gon.com/showthread.php?t=329300
     
  4. jib

    jib Central OR Active Member

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    That's a long winded topic :sleep: You can do every thing right except the crimp and you'll have a problem. For semi-auto, the round will head space in the barrel off the case mouth to much crimp will mess this up. Too little crimp can cause feed issues when the case flare is not completely removed or the bullet is set back from cycling when the case neck tension is not sufficient to hold the bullet in place.
    If I feel I have good case tension on the bullet I will remove the flare and give it a wee bit more squeeze ;)

    PS
    A thermos keeps stuff hot or keeps stuff cold. How does it know :D
     
  5. Gunner3456

    Gunner3456 Salem Well-Known Member

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    Wavo, almost a touch off-topic, but be aware that a different brand or same brand and different type of bullet will require a different adjustment to the seating die to get the same overall length (OAL) with your cartridges. The die simply contacts the different shape of the bullet differently.

    Maybe you already knew this, but it wouldn't be possible to set up a seating die and crimp die combo without having the actual bullets you're going to be using.

    Nothing wrong with playing around and experimenting, though. :thumbup:
     
  6. actionflies

    actionflies Beaverton, Oregon Member

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    You only need a little crimp for any semi caliber and more crimp for magnum load. The best way to find how much crimp you need is to measure a factory round.
     
  7. Yankeefan

    Yankeefan Southern Oregon Member

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    The best way, I have found, to see if you have enough crimp is to simply go through the loading process. You'll feel the tension when you press the loaded round up into the crimp die and yes you can feel, and see, when you've crimped the round to much. Just set-up the crimp die according to the manuf. instructions and adjust to your needs.
     
  8. NWPilgrim

    NWPilgrim Portland area Member

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    I have found a good taper crimp for pistols is to crimp until the case mouth is .001" less than max case mouth outside diameter as indicated in the cartridge drawing.

    Some of the really tough to pull bullets have been sealed with a tar like sealer or lacquer. This is more typical of military style ammo. Also, the lighter the bullet, the less inertia working for you.
     
  9. ogre

    ogre Vancouver, WA Well-Known Member

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    As an aside; a useful way to get those bullets out of the case that have been sealed in with that tar-like substance is to seat them slightly deeper to break the seal and then go ahead and whack them out.
     
  10. the4thshake

    the4thshake Portland Active Member

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    Anyone use the Lee factory crimp die? I don't load for handguns but use it for most of my rifle reloading.
     
  11. motoman98

    motoman98 Gresham, OR Active Member

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    When loading straight walled pistol cases, you are taper crimping as has been posted. This operation is sensitive to correct die adjustments, in my experience.
    Take a completed round and make sure that you cannot move the seated bullet. To test, take a loaded round and push the bullet firmly against the edge of your loading bench: it should not move into the case. This is very important.
    If bullet 'set back' occurs, dangerous pressures can occur.
    Adjust so this cannot happen.
     
  12. actionflies

    actionflies Beaverton, Oregon Member

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    I do for all my handgun calibers and never had a problem.
     
  13. Gunner3456

    Gunner3456 Salem Well-Known Member

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    +1 on the separate Lee crimp dies, especially if you have a 4 die turret. Otherwise the seating die will also crimp.


    Also, if you over-crimp (set die too low) a case you can bulge the case out and get feeding and extracting problems. Not a good thing for a newbie to learn the hard way, and don't ask me how I know. :D It might appear that you couldn't due to the die slipping down over the case and that does help, but if pushed enough, even brass can get "spring" in it and bulge out.
     
  14. wavo

    wavo Portland Member

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    Thanks for all the responses on this. I do have the factory crimp die but just used the bullet seating/crimp die and it seems to be a strong enough crimp. I will find out tomorrow! Made my first 50 complete rounds tonight and decided to stop there until I can test them out tomorrow. Wish me luck! I must've checked and rechecked my grains and OAL a hundred times. Better to be safe and slow than fast and mangled hand. :thumbup:
     
  15. ZeroRing

    ZeroRing 26th District, WA Active Member

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    Yup, you've got the right idea. Concentrate on "perfecting" your system and accuracy and worry about the "speed" later. :thumbup:
     
  16. Gunner3456

    Gunner3456 Salem Well-Known Member

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    Congratulations. Now you're hooked. :)
     
  17. wavo

    wavo Portland Member

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    Woohoo! I fired my first 50 rounds and everything went off without a hitch! Boss left for the day so the 2nd in charge turns to me and says "why don't you go take a 2 hour lunch break or something?" I jumped at the chance, ran home grabbed my gun and freshly made ammo and headed to Johnson Creek. T'was perfect, not to mention there was at least 150 casings of 9mm in the bucket when I go there, double score!

    Anyways, just excited at the moment, I'm sure this is nothing big to all the master reloaders out there :laugh:
     
  18. Gunner3456

    Gunner3456 Salem Well-Known Member

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    Congratulations. That's a great feeling, I know. :thumbup:

    If you don't mind a wet blanket, I'd throw those casings away. I simply won't reload unknown casings unless I have no choice. 1,000 once-fired, matched head stamp, indoor range pickup 9mm casings won't cost you that much on gunbroker, and you can reload them several times if you don't abuse them.

    Also, you will get different results from different brands and types of brass. You can prove it with a chronograph. You'll get different pressures due to different case wall thicknesses and base thicknesses. You'll get different gripping results on the crimp. It may well affect accuracy, not to mention safety if any case has been loaded too hot as a reload.

    It takes a while and some coin to build up a stock of good brass, but it's worth it if you can.

    $.02
     
  19. toolfan

    toolfan North Portland Member

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    Chances are, all that brass from the range is nice once fired stuff. People who reload tend to pick up what they shoot.

    Visually inspect it, Sort it by headstamp and/or weight if you want to go crazy, or just don't use it for max or near max pressure loads.
    :thumbup:

    If you aren't comfortable, I'm sure someone would give you at least a couple pennies a case for it. :laugh:
     
  20. Gunner3456

    Gunner3456 Salem Well-Known Member

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    Sorry, Nope. Every brand of brass will have different case wall thicknesses and different base thicknesses. The volumes in the cases will therefore be different. Identical loads in those cases will therefore develop different pressures and shoot to a different point of aim. A smaller volume case will develop pressure much faster, too.

    Even the crimp strength will be different due to the different case wall.

    I just bought 1,000 matched indoor LEO range 9mm cases on gunbroker for $30 including shipping. I can reload them at least 5 times. That's .6 cents, or about a 1/2 cent per round for using quality matched brass.

    With all the work involved, and the cost of quality components, it's not worth the tiny savings per round to scrounge unknown, mixed brass even if you did know they were once fired.

    One of the nicest things about reloading is that you can tune a load to your unique gun for accuracy. That's not even thinkable with mixed brass. Even if one doesn't tune loads, but just reloads by the book, he'll still have mixed accuracy with mixed brass.

    Why bother?

    $.02