Quantcast
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

why roll crimp for semi auto 30/06

Discussion in 'Handloading and Reloading' started by m715, Jan 12, 2013.

Thread Status:
Not open for further replies.
  1. m715

    m715 Member

    Joined:
    Dec 18, 2012
    Messages:
    30
    I reload for my rem700 30/06 bolt action.I also have a 742bdl semi auto.I would like to run reloads through the semi as well.Seems I remember reading somewere that to reload for semi auto The bullet must be roll crimped.I taper crimp for the bolt action and have no problems.My question is why do you need to taper crimp for the semi but not for the bolt action.
     
  2. 243winxb

    243winxb Member

    Joined:
    Jul 7, 2004
    Messages:
    9,130
    Location:
    Hopewell Big Woods
  3. rcmodel

    rcmodel Member in memoriam

    Joined:
    Sep 17, 2007
    Messages:
    59,082
    Location:
    Eastern KS
    How do you do that?

    No 30-06 seating die I am aware of has taper crimp capability.

    The fact is, if your case neck tension is as it should be, there is no need at all to crimp for anything less then an elephant rifle or a tubular magazine like a 30-30 lever-action.

    In those instances, recoil can pound the bullets back in the cases.

    You have no such issues in your 30-06 bolt-action, and if the semi-auto feeds right, there should be no such issues with it either.

    rc
     
  4. Ifishsum

    Ifishsum Member

    Joined:
    Jun 21, 2005
    Messages:
    939
    Location:
    Portland, OR
    If he's taper crimping I assume the OP is using a Lee set with a FCD.

    This is my take - loading manuals recommend crimping loads for semi-auto actions because it's the safest way, and it's the same reason all factory ammo is crimped. The casual reloader may not pay a lot of attention to neck tension, or even know whether it's good enough on the cases they're loading. Crimping adds insurance against a bullet getting pushed back into the case and possibly raising pressure to a dangerous level. When making a recommendation to a relatively new reloader or to someone who's proficiency I don't know, I'd also recommend the safest method. Personally, I don't crimp every round I load for a semi-auto rifle but when I'm using a bullet with a cannelure I usually do - because I haven't found a reason not to.

    Pretty much all rifle seating dies make a roll crimp rather than a taper crimp. The extra Lee FCD is the only exception I'm aware of, but the standard for rifle dies is a roll crimp. That's likely why you saw that recommendation. If the bullet has a cannelure - and if you're going to crimp it - I believe a properly applied roll crimp is probably more secure than a taper crimp.
     
  5. rcmodel

    rcmodel Member in memoriam

    Joined:
    Sep 17, 2007
    Messages:
    59,082
    Location:
    Eastern KS
    The Lee rifle FCD does not taper crimp either.

    It collet-crimps a depressed ring around the case mouth.

    rc
     
  6. cfullgraf

    cfullgraf Member

    Joined:
    Oct 19, 2010
    Messages:
    7,247
    Location:
    East TN
    I have a Lee 30-06 taper crimp die. It is not an FCD. It is not a seater die.

    But, I have not crimped any reloads for my Garands in 8 to 10 years.
     
  7. m715

    m715 Member

    Joined:
    Dec 18, 2012
    Messages:
    30
    Ihave an rcbs fl sizer and rcbs seat die.
     
  8. USSR

    USSR Member

    Joined:
    Jul 7, 2005
    Messages:
    8,518
    Location:
    Finger Lakes Region of NY
    As previously stated, no need to crimp for either of your rifles, it's all about neck tension.

    Don
     
  9. Captaingyro

    Captaingyro Member

    Joined:
    Nov 27, 2008
    Messages:
    419
    Location:
    Greater Waxhaw Metropolitan Area (NC)
    Just to clarify, pounding the bullet back deeper in the case would indeed be the danger in a rifle with a tubular magazine, but in an elephant rifle (usually a side-by-side double) or the OP's 742 with it's box magazine, the bullets being jerked forward in the case under recoil would be the concern.

    One technique for determining if your neck tension is adequate in that case: Measure the OAL of a finished round, then load it into your kinetic bullet puller. Give it a whack quite a bit harder than any recoil you anticipate, and measure it again. If it hasn't grown, you're GTG.
     
  10. rcmodel

    rcmodel Member in memoriam

    Joined:
    Sep 17, 2007
    Messages:
    59,082
    Location:
    Eastern KS
    A double-rifle pulls bullets because the rifle recoils, and the bullet in the 2nd. barrel tries to stay where it was, while the case is jerked away from it.

    A box-magazine rifle pounds them deeper in the case because the whole round is trying to stay where it was, while the magazine they are in is accelerated rapidly to the rear.
    (Witness flattened lead bullet tips on the ones you don't shoot.)

    Nothing in a box magazine has a hold of the round to yank it off the bullet, or squirt the bullet out of it.

    rc
     
  11. Captaingyro

    Captaingyro Member

    Joined:
    Nov 27, 2008
    Messages:
    419
    Location:
    Greater Waxhaw Metropolitan Area (NC)
    Take a look at one of your AR mags. There is indeed something that will hold the case back, while the bullet is free to move forward.

    See that vertical rib that's stamped (or molded) into the side of the mag? It engages the case at the shoulder, and prevents it from moving forward more than a slight amount. There's a little slop built in, of course, so rounds that are loaded right to max mag length could contact the front of the mag and be set back. Normal length rounds, however will be stopped by the shoulder and the possibility of bullet pullout exists.
     
  12. rcmodel

    rcmodel Member in memoriam

    Joined:
    Sep 17, 2007
    Messages:
    59,082
    Location:
    Eastern KS
    I thought we were talking about Remington 30-06's.

    You can hardly pull a .223 bullet with a bullet puller and 40 whacks anyway.


    rc
     
  13. Captaingyro

    Captaingyro Member

    Joined:
    Nov 27, 2008
    Messages:
    419
    Location:
    Greater Waxhaw Metropolitan Area (NC)
    I assumed you'd be able to put your hands on an AR mag easier than a Rem 742 mag. Here's the 742 mag in .30-06:

    [​IMG]
     
    Last edited: Jan 14, 2013
  14. m715

    m715 Member

    Joined:
    Dec 18, 2012
    Messages:
    30
    guess i will take my 742bdl and garand out with some of the reloads.I thank I will run all but the last one of a full clip through the gun,I will remove the last round from the chamber and measure it.If the last round does not grow I would have to be ok.
     
  15. m715

    m715 Member

    Joined:
    Dec 18, 2012
    Messages:
    30
    Got out to shoot the loads.I measured the col of first bullet in the clip.fired three of the four rounds through the bdl,then unchambered the last round and measured again.The bullet was .003 shorter than when I loaded it.Did the same thing for the garand.fired seven of the eight measured the last round it was .007 shorter than when I loaded it.I read the link that 243winxb posted.The neck tension makes since.Would the lee factory cimp die do the same thing.From what I read it sounds like that die squezes the neck of the case instead of roll crimping it.Did I read the description of the die correctly?
     
  16. rcmodel

    rcmodel Member in memoriam

    Joined:
    Sep 17, 2007
    Messages:
    59,082
    Location:
    Eastern KS
    Yes you did.

    The Lee FCD collet crimp die squeezes a ring on the case mouth into the bullet cannulure.

    rc
     
  17. Walkalong

    Walkalong Moderator

    Joined:
    Nov 20, 2006
    Messages:
    47,607
    Location:
    Alabama
    C&H makes a .308 taper crimp die, and perhaps a .30-06, I don't know, and it would work to taper crimp .30-06 if one desired.
     
  18. m715

    m715 Member

    Joined:
    Dec 18, 2012
    Messages:
    30
    o.k. so I should reduce the resizer ball on my die by .001 to .002 under bullet dia to get the neck tension I need to fire the non canalure bullet that I use in my 06 bolt action to prevent the bullet from moving if I want to fire it in the bdl or garand.Now I wander if the bullets in the bolt action that are in the clip when firing are also getting shorter?
     
  19. USSR

    USSR Member

    Joined:
    Jul 7, 2005
    Messages:
    8,518
    Location:
    Finger Lakes Region of NY
    If you are able to grasp a loaded round by the case and press down on a table with the bullet and have the bullet slip further into the case, then yes.

    Don
     
  20. soloban

    soloban Member

    Joined:
    Sep 8, 2009
    Messages:
    466
    Location:
    Madison, AL
    I FL size my .30-06 with a Redding Die and seat with a competition seater using 150gr SMKs. No crimp, never had an issue in my M1 at all.
     
  21. tahoe2

    tahoe2 Member

    Joined:
    Dec 26, 2011
    Messages:
    807
    Location:
    Seattle area, Washington state
    Rem 7400/280 Rem

    I have been reloading for this one for over ten years, from 130grns to 160grns and everything in between without a bobble.
    My secret is not a secret--LEE--"factory crimp die"
     
Thread Status:
Not open for further replies.

Share This Page