CRIMPING 223 FOR SEMI AUTO

Discussion in 'The Ammo & Reloading Forum' started by bamashooter, Feb 25, 2010.

  1. bamashooter

    bamashooter New Member

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    north alabama
    Ive been reloading for awhile,but havent reloaded for a semi auto. Its always been for a bolt action or single shot.
    My question is; is there any need to crimp? Some of the rounds i will shoot and some will be put in my stash. i just want to do what is necessary to insure that they are safe and reliable.
    By the way im loading 60gr. hollow point seirra varmiter, with IMR-4895. Looking at about 2800fps.
  2. bucksnducks

    bucksnducks New Member

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    I like the Lee Factory Crimp Die.
    If it's semi-auto anything, I give it a crimp.
  3. steve4102

    steve4102 Former Guest

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    From the experts at 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 to complete article.

    http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm
  4. LDBennett

    LDBennett Well-Known Member

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    Semi-Auto ammo must be crimped. The easiest way is with the Lee Factory Crimp Die. It is easy to set up and the resultant crimp hangs on tight.

    Remember every round in the magazine is in the gun during firing and subjected to the recoil multiple times except the first round. The poor last round has to endure many recoils! As stated above the feeding operation is violent and can move the bullet in the cartridge case. The bullets NEED to be crimped.

    LDBennett
  5. steve4102

    steve4102 Former Guest

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    Hey LD, what do you know, we finally agreed on something!
  6. old semperfi

    old semperfi New Member

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    i live in southern indiana,old country boy at hear
    i have used the lee factory crimp for years in both semi auto and bolt action,no contest-------lee old semperfi
  7. LDBennett

    LDBennett Well-Known Member

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    steve4102:

    I'm sure we agree on a lot of stuff. There is a lot of stuff in guns and reloading that are open for disagreement and apparently you and I have touched on several of them recently.

    I don't care how anyone does there guns or reloading. I only care that if it is done unsafely that the process or idea is not picked up by someone who is new or unknowledgeable about guns or reloading. So I am quick to point out the way to do it safely and may even express my way or my opinion. But we all get to choose and I want a newbie to not make a safety mistake. I also like to keep newbies from making all the mistakes of choice I made through the years. We all learn from our mistakes but it is better to learn from the mistakes of others and not make the mistakes yourself.

    Here's to more friendly disagreements!

    LDBennett
  8. bamashooter

    bamashooter New Member

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    thanks for the info guys. i bought a lee factory crimp die and will definatly use it.
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