Reloading, to crimp or not to crimp

steve4102

January 25, 2004 17:39

I am about to start reloading for my Ruger Mini30 7.62x39. My reloading dealer set me up with a .308 135gr.SP Sierra Pro Hunter. This bullet has NO cannelure groove for crimping. I asked my dealer about crimping and he said I need to crimp for this gun and the lack of a cannelure is NOT a problem. However, in my Speer loading manual it says that crimping must be done only if the cannelure is present, without the groove the crimp could damage the jacket and reduce accuracy. What should I do?
Thanks
steve

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  v35

  January 25, 2004 17:53

  Crimping for semiautos is insurance that bullets will not be bumped back in the case during its' rough handling in the chambering cycle.
  When this happens, pressures can rise and be dangerous.
  You can compare accuracy of uncrimped reloads chambered singly by hand with those given a light bump crimp and fed through the magazine.

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  p3skyking

  January 25, 2004 18:50

  While it's true you can slightly deform the projectile if no cannelure is present, I would still crimp. The 7.62X39 is not known for one hole groups anyway. I think Lee still makes a taper-crimp die, use that if you are really concerned.
  
  
  
  What men call a hero...is merely a man who is seen doing what a brave man does as a matter of course.
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  richbug

  January 25, 2004 19:02

  The die you want to use is a Lee factory Crimp die. They are about $10 from Midway or Midsouth. They are a collet type mechanism which actually makes a canalure when the bullet doesn't have one. A crimp is a good Idea in autos or lever guns.
  
  My border collie is smarter than your honor student.

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  leeblackman

  January 26, 2004 13:20

  I basically look at it this way. If your not shooting single shot then you need to crimp. This is because during the cycling of any repeating weapon, the bullet is generally bumping a feed ramp and the top of the chamber, and if you don't have a little crimp on it then it might be pushed into the case. I'm not saying you need to locktite the bullet in place or anything, but it need to be properly seated. You can test you crimp by loading a "dummy" round with no primer or powder and cycling it thru the action of your gun several times to see if the bullet seat changes during operation. If you over crimp then you can have problems with accuracy because of bullet deformation. Follow the directions that came with your die set. Usually the seating die also crimps and you can adjust it.

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