To Crimp or not to Crimp

Discussion in 'Ammunition and Reloading' started by Hilborne, Jan 6, 2008.

  1. Hilborne

    Hilborne New Member

    19
    0
    0
    I reloaded my first 100 rds of 40 S&W and finally got to shoot them. All went well with the exception of two failures to get into full battery. I later shot both of those round's without a problem. Now I'm ready to start loading some more, and wanting to get it right am wrestling with wether to tapper crimp or not. My Lyman loading manual says not to roll crimp (that makes logical sense), and I quote "A modest taper crimp may be employed if found necessary". I've noticed some post on other boards that apparently some people do crimp, so what do I do?

    I'm using a single stage RCBS II press with a Lee set of dies. Any comments?

    Andy
     
  2. Shooter

    Shooter Premium Member

    1,689
    7
    38
    I crimp all my ammo for semi-auto with Lee factory crimp dies....it is probably the best, low cost crimper....if a round gets a little compressed if it hits that ramp a little hard the bullet could be pushed down into the shell a bit. that would compress the load and maybe increase the pressure of the round (therorizing here :think: ). I would crimp........
     

  3. nixon

    nixon Member

    156
    0
    16
    Shooting semi-auto round always need ammo to be taper crimped. How tight depends on the type of bullet you're using. I agree with Shooter's assertion. Lead or plated bullets need more crimp than jacketed ones because they are softer and therefore prone to get pushed back when hitting the feed ramp. Use your visual judgment. Currently I use plated bullets and my crimp is slightly tighter than I would with jacketed.
     
  4. ppro

    ppro Guest

    7
    0
    0
    Taper crimp, no roll crimp for the semi autos and watch the amount of crimp you apply. You can over crimp even with the taper crimp die. Watch that you don't create a ever so slight bulge just below the taper crimp...which can affect feeding. Use your dial calipers and check how much you are crimping and write it down for a base line reference. Redding makes a very nice taper crimp die.

    Paul
     
  5. MrApathy

    MrApathy Active Member

    1,085
    5
    38
    amount of taper crimp depends on the bullet your using and load.
    lead or plated use small amount of taper crimp otherwise you can wind up sizing the bullet down
    in the case of plated you can cut into the plating. can affect accuracy.

    with jacketed you can size a little more though depends on how soft the lead is.

    most cases you just want the casemouth to be flush with the bullet.
    crimp should be about casemouth thickness x2 + bullet diameter.
     
  6. Hilborne

    Hilborne New Member

    19
    0
    0
    Thanks for the good comments. I went ahead and made up a hundred rounds with my Lee three die set just bumping the case a little bit with the bullet seating die. I can see from my results that a crimping die would be a valuable addition. Live and learn, I bought the Lee 3 die set because the day I wanted it, it was what was available. I bought on price, the four die set is more dollars, but at the time I didn't understand the function of the fourth (crimping) die.

    As a side note I bought 1,000 rounds WB40TC165 40 S&W 165 gr TC, from http://www.tjconevera.com/index.html
    $93.00, and he paid the shipping. This is the same bullet that you get when you buy Walmart White boxes.

    Andy