+ Reply to Thread
Page 1 of 3 123 LastLast
Results 1 to 10 of 24
Like Tree23Likes

Thread: Why do we Crimp?



  1. #1
    Site Contributor Contributing Member
    Join Date
    Mar 2007
    Location
    Southwest ID
    Posts
    6,017
    Member #
    3315
    Thanked
    5506 times

    Why do we Crimp?

    .

    Why do we crimp the 45-70 with a heavy crimp? Any crimp that will prevent the bullet from moving back into the case should be adequate and that would be just enough to catch the crimp groove. A very light crimp that is nearly invisible. I have heard of a number of disadvantages to heavy roll crimp and the LFC on cast bullets.
    capt greg and Plano like this.

  2. #2
    Certified Gunnut
    Join Date
    Jan 2005
    Location
    Star, Idaho
    Posts
    4,130
    Member #
    1128
    Thanked
    7454 times
    I don't use a heavy crimp; moderate, to insure consistent ignition shot to shot. Higher velocities can be obtained from a moderate crimp vs no crimp, which we learned while taking those readings a couple of weeks ago.. BUT I agree a heavy crimp does nothing for you except build unneeded or unwanted higher pressures.
    1895Gunner, Plano and Josper like this.

  3. #3
    Site Contributor Contributing Member
    Join Date
    May 2006
    Location
    Idaho and Arizona
    Posts
    4,160
    Member #
    2182
    Thanked
    533 times
    I agree completely JB

    The bullet is held in place by neck-tension, not by the crimp. No matter how heavy the crimp may be, it can never hold the bullet in place without proper neck tension.

    So, the answer to your question is – the crimp is just for looks and to keep the edges of the case mouth from hanging up in the action during cycling.

    Oh – and I too despise that Lee FCD for use with cast bullets in the 45-70…
    Danny

  4. #4
    Contributing Member
    Join Date
    Apr 2004
    Location
    Ct
    Posts
    6,859
    Member #
    487
    Thanked
    6860 times
    Never used a LFCD on 45-70................Or anything else for that matter, But I agree, only enough crimp to reliably keep the bullet from moving is all that is necessary...............
    I think most Rest Shooters would agree....................

    IF, you use a heavy crimp, and your die is biased to a stronger crimp on one side...........you'll not get repeatable POI accuracy unless you "Clock" each bullet into the chamber exactly as it comes out of the seating/crimping die............and even then, other parameters (varibles) come into play.

    Tom
    NRA LIFE
    CCDL

    Treat others the way you want to be treated.

  5. #5
    Gunfighter
    Join Date
    Nov 2011
    Location
    co
    Posts
    913
    Member #
    26085
    Thanked
    763 times
    I agree..I dont think a heavy crimp is needed.. Just enough to keep the bullet secure.. the only rifle rounds I do crimp is tube fed rounds.. my bolts, ar's, single shot's I dont crimp.
    Sweetwater likes this.
    However complicated the issues become... it comes down to one simple question. Which is more important to you Life or Liberty? I've made my decision long ago.

    "Is life so sweet or peace so dear; as to be paid for at the price of chains and slavery? Forbid it Almighty God I know not what course others may take, but as for me, give me Liberty or give me Death." Patrick Henry

  6. #6
    Sidewinder
    Join Date
    Feb 2011
    Location
    Pittsburgh, PA
    Posts
    110
    Member #
    21084
    Thanked
    8 times
    I also agree that a light to moderate crimp is needed for tube fed rounds. This keeps the bullet secure and helps with consistent pressure.
    I also put a light crimp on my 300 weatherby rounds to keep the bullets from being pushed back under recoil while in the magazine.
    Plano likes this.
    The High Tech Redneck
    1895GBL 45-70
    Team .45/70 member #294

  7. #7
    Marlin Marksman
    Join Date
    Sep 2010
    Posts
    1,646
    Member #
    18131
    Thanked
    978 times
    What's the downside to a lfc die and cast bullets?

  8. #8
    Site Contributor Contributing Member
    Join Date
    Mar 2007
    Location
    Southwest ID
    Posts
    6,017
    Member #
    3315
    Thanked
    5506 times
    Quote Originally Posted by rooterpig View Post
    What's the downside to a lfc die and cast bullets?
    The Lee Factory Crimp distorts the bullet which in turn diminishes accuracy. A heavy roll crimp does similar distortion to the bullet. Contrary to popular belief, a crimp does not aid ignition or contribute to consistent velocities. Test that I ran with Kid Sopris shooting the 45-70 showed an average deviation of 61 feet per second for ammo with a moderate crimp. Ammo with no crimp showed an average deviation of only 24 FPS. So which is consistent? And if a crimp is good why don't the Bench shooters use a crimp?

    Another issue that I have found with a crimp is the very slight bulge that it causes at the case mouth where the crimp tool rolls the case over into the crimp. That makes crimped rounds hard to chamber on rifles with a tight chamber (38-55 CB). Several reloaders on this forum have complained of this, thinking that the cause is COAL or a bullet issue when it could be simply too much crimp. Since the chamber is tapered, shortening the case length moves the crimp roll back just enough to alleviate the issue and the reloader thinks the case length/COAL was the issue.

    Think about it, then draw you own conclusions.

    Regards
    Sweetwater, 4Charlie and Plano like this.

  9. #9
    Marlin Marksman
    Join Date
    Sep 2010
    Posts
    1,646
    Member #
    18131
    Thanked
    978 times
    So your no worse off with a lfc than a roll crimp? They both distort the the cast bullet to a degree? Veral talks about loading a cast bullet on top of a compressed powder charge, with no crimp ,and it (cast bullet)not moving.
    Last edited by rooterpig; 08-16-2012 at 04:09 PM.

  10. #10
    Certified Gunnut
    Join Date
    Jan 2005
    Location
    Star, Idaho
    Posts
    4,130
    Member #
    1128
    Thanked
    7454 times
    Well Jim has a valid point, but there is more to play here. If we chose Brass with a consistent rim diameter and held trim length to .001 +/-, coupled with a a consistent bullet diameter; in other words play the PITA game the Bench rest shooters do, then yes Crimping doesn't mean anything. However I think the average reloader, buys a bag/box of Starline brass, maybe trims for OAL and does his thing.

    I have found inconsistent diameters in bullets from all manufactures and the same with rim diameter on Brass. A change of +.001 at any one point on brass will change the crimp on any bullet.

    I think for the average shooter our +/- .001 still provides reliable accuracy at most given distances for hunting purposes. Ringing the gong at 200 yards is not as critical as ringing it at 600 yards, assuming the targets are the same size.

    I think when you factor in the type of Powder, coupled with the load density Bullet dynamics change from load to load.

    I also think as reloaders we have to decide what is best for each of us. JBledsoes' loads, and I have shot them out of my Marlins, are very accurate. However, if I am hunting and the rounds may be exposed to environmental elements couple with my crawling around or falling down, (Lord Forbid), I wouldn't want a round to be pushed into a case creating excessive pressure that could prove to be a problem in the field.

    If in Fact I was going to load some rounds for the Bench only, I would buy another seating die and mark it as such for NON CRIMPED loads, as I hate to mess with perfection....
    Sweetwater, dhansen and rooterpig like this.


Home | Forum | Active Topics | What's New | Subscribed Threads

Links

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts

Similar Threads

  1. To Crimp OR Not to Crimp 45-70 Single Shot
    By iraqvet13f in forum The 45/70 Govt.
    Replies: 33
    Last Post: 02-20-2012, 12:27 AM
  2. Replies: 7
    Last Post: 08-08-2011, 06:26 AM
  3. Not enough crimp edge on lee factory crimp
    By gohip2000 in forum Reloading
    Replies: 1
    Last Post: 05-13-2007, 04:33 PM
  4. Lee Factory Crimp Die uneven crimp?
    By JLarsson in forum The 444 Marlin®
    Replies: 2
    Last Post: 09-25-2006, 04:47 PM
  5. Lee Factory Crimp Die uneven crimp?
    By JLarsson in forum Reloading
    Replies: 8
    Last Post: 09-25-2006, 04:45 PM

Search tags for this page

.444 is crimping necessary for single shot rifle
,
444 light crimp
,

45-70 remington center case crimp

,
bullet crimp groove 4570 jacketed
,
crimps not holding on cast
,
how to crimp cast 45-70's
,
lee reloading crimp for accuracy forum
,

uneven crimps

,

why do we crimp wire

,

why is my crimp die only crimpping one side

,

why we use crimping

Click on a term to search for related topics.