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223 crimp

Discussion in 'Reloading' started by smanocchio, Jul 26, 2012.


  1. smanocchio

    smanocchio
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    So I'm getting around to loading 223 for my new AR build and have done plenty of research on whether or not to crimp and have found everybody likes doing their own thing. There does not seem to be a definitive answer.

    I decided to try no crimp with my first rounds loaded. I used hornady 55gr FMJBT and NEW Remington brass. I found that after chambering a round the OAL will grow a small amount, maybe .002 inches each time (letting the bolt slam home).

    Is this normal? Do any of you guys that do not crimp 223 experience this as well? Should I start crimping to prevent it from happening?
     

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  2. MStarmer

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    Did you size the brass first? Even new brass should probably be sized just to get any dings out of the neck etc.. Before this turns into a troll thread the general rule / guesstimate is that for an auto loader a light crimp is desired to keep the bullet from moving either forward or back. On a bolt gun it is not. As you found many many people have an opinion on this and it varies widely. I put a gentle crimp with a Lee FCD on my .223 rounds just trying to ensure even tension. I'm not too worried about set back as I'm already running compressed rounds. Try it both ways and see what works for your brass. If you're running a chrome lined barrel that's only going to give you 2 or 3 moa a crimp isn't going to kill your accuracy, or if you are shooting close in. If you are shooting groups at 300 the crimp may worsen your groups.

    This is the same as full length resizing, most people will full length for an autoloader and only neck size for a bolt gun.
     

  3. F106 Fan

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    If the bullet has a cannelure, I would crimp it. The Montana Gold 55gr FMJBT has a cannelure so I do crimp it. MANY other .223 bullets do not have a cannelure and probably shouldn't be crimped.

    I have always thought that the crimp was to prevent the bullet from moving back in the case during recoil (magazine fed guns) and, since a cartridge is only chambered once, the little bit it grows doesn't really concern me.

    I just measured one of my reloads and it grows by 0.001". Not much of a sample so I'm not drawing any conclusions.

    I guess I could increase the amount of crimp in an attempt to hold the bullet stationary but before I do that I want to see what happens with Wally World Federal bulk because it also uses a 55 gr bullet with a cannelure and it is crimped.

    Richard
     
  4. steve4102

    steve4102
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    This is from Sierra.

    Neck Tension

    When we stop to consider the vigorous (read, downright violent) chambering cycle a loaded round endures in a Service Rifle, it becomes pretty clear it suffers abuse that would never happen in a bolt-action. This is simply the nature of the beast. It needs to be dealt with since there is no way around it.

    There are two distinctly different forces that need to be considered: those that force the bullet deeper into the case, and those that pull it out of the case. When the round is stripped from the magazine and launched up the feed ramp, any resistance encountered by the bullet risks having it set back deeper into the case. Due to the abrupt stop the cartridge makes when the shoulder slams to a halt against the chamber, inertia dictates that the bullet will continue to move forward. This is exactly the same principle a kinetic bullet puller operates on, and it works within a chamber as well. Some years ago, we decided to examine this phenomenon more closely. During tests here at Sierra’s range, we chambered a variety of factory Match ammunition in an AR-15 rifle. This ammunition was from one of the most popular brands in use today, loaded with Sierra’s 69 grain MatchKing bullet. To conduct the test, we chambered individual rounds by inserting them into the magazines and manually releasing the bolt. We then repeated the tests by loading two rounds into the magazine, chambering and firing the first, and then extracting and measuring the second round. This eliminated any potential variation caused by the difference between a bolt that had been released from an open position (first round in the magazine) and those subsequent rounds that were chambered by the normal semi-automatic operation of the rifle. Measuring the rounds before chambering and then re-measuring after they were carefully extracted resulted in an average increase of three thousandths (0.003") of forward bullet movement. Some individual rounds showed up to seven thousandths (0.007") movement. Please bear in mind that these results were with factory ammunition, normally having a higher bullet pull than handloaded ammunition.

    To counteract this tendency, the semi-auto shooter is left with basically two options: applying a crimp or increasing neck tension.


    Link:
    http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm

    I crimp with the Lee Factory Crimp die, both cannelured and non-cannelured bullets. Works well for me, helps secure the bullet and accuracy is a touch better.
     
  5. steve4102

    steve4102
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    I did a little test a few weeks ago with my AR and the Lee Factory Crimp die.

    To make a long story long, I have always used the Lee Factory Crimp die when loading for semi-autos. I tested the LFCD for accuracy a long time ago, my tests showed enough improvement in both securing the bullet and in accuracy that I have blindly used it ever since. Lately I have read that many handloaders are having mixed results with the LFCD and most of it bad.

    With all this negative talk about the Evils of the LFCD, I started to second guess my previous accuracy tests. Maybe I wasn't getting the improved accuracy I thought I was. So, I loaded up a few rounds with the crimp and a few without and headed off to the gravel pit.

    The rifle was a Colt HBAR off the shelf AR-15 5.56.

    This first target was Sierra 53gr HP Matchking with 25.5gr AA 2520. The heavy crimp was "heavy" a pulled bullet showed a deep groove in the bullet. The Med-light crimp showed a slight ring or groove, but just barely.

    [​IMG]

    This next set of targets is all with 53gr Sierra HPMK and 26gr 748. I fired five at the crimp target then five at the No-crimp target, then I reversed it and fired five ant the No-crimp first and so on. My plan was to shoot 25 rounds at each target, but I got booted out of my shooting spot by some loggers hauling equipment into the pit, so I only fired 15 at each target.

    [​IMG]

    [​IMG]

    [​IMG]

    Conclusion. Not enough of a sample to draw and real conclusion whether the LFCD improved accuracy or not, but enough of a sample that it sure as hell didn't hurt. Except for the Heavy crimp, that clearly degraded accuracy.
     
    #5 steve4102, Jul 26, 2012
    Last edited: Jul 26, 2012
  6. smanocchio

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    Even though the brass was new I sized and prepped it all like normal.

    I guess Ill shoot some crimped and un-crimped and see what happens.
     
  7. smanocchio

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    Thanks for the info/pictures :cool:

    I will mess around and try both for the sake of seeing what works best for me and my gun accuracy wise, I was just surprised at the amount of bullet movement with no crimp. Especially with all the people saying there is no point in crimping, even for auto loaders
     
  8. Hoser

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    I don't crimp any of my rifle ammo.
     
  9. smanocchio

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    Do you experience what I described in the first post as well?
     
  10. country85

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    In an AR type rifle IMO you should always crimp. Besides giving you a more complete powder burn, it's a good safety measure. Let's just say you load up a few (not crimping) and head off to the range. You shoot one or two mags with no problem. But the next mag you insert has a bullet that was just a little bit smaller than all the others, so you slam the mag in and drop the bolt. Any other time this would be fine but with a bullet that is slightly under sized there's not enough neck tension to hold the bullet in place. AKA you have a bomb on your hands, best out come you replace a bolt, maybe have to get a new barrel, worse case, well take 20 grains of varget under pressure and light it... I know the "bomb" out come is less likely in a 223 but once you move to an AR10 or other semi auto large cartridge auto's it becomes a real danger!
     
  11. DoctaGlockta

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    I crimp my rifle rounds that get shot out of semi-autos.

    Why? Because I think I read on here that Fred said to.

    I trust Fred.

    Good luck.
     
  12. TX Archer

    TX Archer
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    You're not the only one!

    I just started loading .223 so, as always, I read everything I could but still couldn't decide. Then I read where Fred said he gives a "light crimp". So that's what I went with. A light crimp.
     
    #12 TX Archer, Jul 26, 2012
    Last edited: Jul 26, 2012
  13. Hoser

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    Nope. I run about .005 neck tension and mainly use Hornady 55s and Sierra heavies.

    If you crimp, be sure all your brass is the exact same OAL. If some brass is longer that will result in more crimp as there is more brass to crimp.

    Even on my Full Auto 223 and 300 Whisper ammo I don't crimp.
     
  14. ColoCG

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    I agree with Hozer. I don't crimp any rifle rounds. No crimp, no problems in ar's, good accuracy.
     
  15. freakshow10mm

    freakshow10mm
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    That's my choice. I use a Redding FL bushing sizer die with .245" bushing. Fired many thousands of rounds through my post- '86 M16 without issue.
    Only cartridges used in rifles I crimp are used in leverguns.
     
  16. fredj338

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    I run a very, very light crimp, really just ironing out the case mouth a bit. I don't really see the need unless you rechamber rounds often, I have not seen any significant bullet setback. A 0.002" setback is within bullet nose variation.
     
  17. smanocchio

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    I tried the same thing with some sierra 69gr BTHP's (locked bolt back, inserted mag, and released bolt) and they did not move at all. Tried another hornady 55gr FMJBT and it moved .002-.003 OUT of the case.

    I think I will start giving the hornady's a light crimp (its just plinking ammo anyways). Is it ok to use a smaller OAL to reach the cannelure? Currently at about 1.250 the case mouth is just barely on the cannelure.
     
    #17 smanocchio, Jul 27, 2012
    Last edited: Jul 27, 2012
  18. Boxerglocker

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    I've concluded the same... I run just a slight crimp in my AR ammo just for the reason described by Fred. I an constantly rechambering rounds in matches and training drills.
     
  19. SilverCity

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    Most major ammo manufacturers use at least a light crimp.

    SC
     
  20. fredj338

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    Only with bullets that have cannelurs. Pull some match ammo, no place to crimp a SMK.:dunno: