Taper Crimp

[tul9033]

I switched several months ago from the Hornady roll crimp to the Lee taper crimp die (non-carbide). So far pretty good results and always case gauge.
My question is, I've pulled a few bullets after crimping and have noticed a ring where the case is squeezing the bullet. Is this too much crimp? Seems I've read this could affect accuracy. Any thoughts?

 

[alank2]

Hi,

What caliber? I'm not a fan of the Lee Factory Crimp Die (FCD). I think if a round is sized properly in the first place and then properly taper or roll crimped, that it should case gauge just fine. To me, the FCD is similar to sizing a round again and I'm not sure what it really does for case bullet tension.

Why did you leave the roll crimp and switch?

Thanks,

Alan

 

[Shadowrider]

Depends on how much actual distortion you are putting on them. Plated bullets like Berry's don't like it. If it's jacketed you are probably fine unless you are really cramming them in the die hard. With lead and especially plated, a little dab will do ya.

 

[Nraman]

Hi,

What caliber? I'm not a fan of the Lee Factory Crimp Die (FCD).

I think he is talking about a taper crimp die. That's what I use on most pistol calibers.
I use the FCD on 223 and plan to use it on 357 Sig.

 

[tul9033]

Yes this is the standard Lee taper crimp die http://www.midwayusa.com/viewproduct/?productnumber=274765
I've been using them on all different kinds of bullets; jacketed, lead, Berry's, and Montana Gold. I've been pretty happy with the results but got the taper mainly for lead as a roll crimp just didn't work and the taper seems to work nicely on other bullets. I did notice a ring around the Berry bullets after pulling a couple, but the accuracy was still quite good. These have all been for 9mm and .45.
I had read that the groove put into plated bullets by too much crimp could throw off the accuracy when it hits the lands of the barrel.
I probably should back it off just a bit and see if that groove disappears or lessens, even though accuracy hasn't seemed to suffer.
Just curious if others had any issues with too much crimp on soft bullets.

I think he is talking about a taper crimp die. That's what I use on most pistol calibers.
I use the FCD on 223 and plan to use it on 357 Sig.

 

[Nraman]

I've been using them on all different kinds of bullets; jacketed, lead, Berry's, and Montana Gold.

I taper crimp all auto calibers.
If I remember correctly, Berry's are plated bullets. Plated bullets are a bit sensitive due to the thin plating. They are velocity restricted to around 1200ft/sec to avoid jacket separation.
Too much crimp could damage the thin jacket. That's the only concern I see.
At the same time you want a good crimp to avoid the bullet being pushed back in to the case.
Considering that some bullets have a cannelure and remain accurate, I find it hard to believe that the ring from crimping would be a serious factor.

 

[alank2]

Hi,

I agree that a taper crimp is what you want for 9mm and 45acp. Roll crimp is usually used for cartridges where there is a cannelure to roll crimp into.

My take on crimping automatic cartridges is this: Case tension is what really holds the bullet in place. I only taper crimp them enough to remove the bell used to make bullet insertion easy. This is why I am not a fan of Lee FCD. By sizing both the case and already seated bullet together, I have to think that case-bullet tension is being compromised. This is also why cartridges like 357sig are prone to setback problems - they have very little case-bullet tension area. You can pile them full of a powder that prevents setback, but most manufacturers glue them!

Good luck,

Alan

 

[Randall]

alank2 has it right,taper crimp for autos just to remove the bell,proper case sizing holds the bullets in place.I roll crimp for revolvers to prevent bullet pull out on recoil with heavy loads.I have a Nowlin I used to use the Lee FCD in .45 Auto and accuracy suffered from sizing the bullets down in the case,went back to a taper crimp and Remington brass for its thin walls and no more problems.

 

[panayoti01]

you only need enough crimp to keep the bullet from getting set back during feeding and recoil effect when the round is in the mag.

i scribe a line on the bullet after seating and crimp. push agains the bench with your thumb. it shouldn't move. you might try backing off the die a shade and check for movement.

bullet set back can increase chamber pressure in 9mm. (it can in any caliber but 9mm is more suseptable due to higher pressures and small case capacity)