Taper or Roll crimp

[Harry]

I have read several threads here concerning taper vs. roll crimps. I am somewhat confused. From info I've read, it seems that semi auto pistols should use taper crimps exclusively. If this is true, why does the Lyman carbide 3 die set for the 40 S&W/10mm auto not include the taper crimp die? I have a Sprinfield XD40 SC. Looks like I'll have to buy a seperate taper crimp die. Right?

[theperfessor]

Until I got a taper crimp die for .45 ACP I would just run my loaded rounds up into the sizer die about 1/16" to turn in the flare. Worked fine, I just hated to unscrew the decapping pin and readjust the lock ring all the time. Don't run it in any further than necessary, you don't want to resize the bullet. I use just enough flare to prevent shaving bullet so mine don't take much.

Drop a loaded round into your barrel (removed from gun!) to make sure it will chamber freely.

[Echo]

The regular seating die can be used to turn the flare in without generating a real roll crimp. Just adjust the die so that it does not touch the shell holder at top center, maybe 1/32". Set it out far enough so that when seating the boolit the crimp step will just turn the case in. Really not that tricky.
>
But.
>
It would be best to get a taper crimp die.

[Harry]

Thanks for the replys. If I reload jacketed bullets, I may not need any crimp if I don't expand the neck too much, if any. With cast, I will use your suggestions.

[mike in co]

a slight taper crimp is a good thing in an auto...prevents the edge of the case from causing a miss feed.
doing the crimp in a fourth operation is even better.

getting a consistant crimp is best, but in most semi auto hand guns( not talking bullseye shooting), it is often not a big thing.


the best of both worlds, trim all your brass to one length, and all your crimps will be very consistant.


mike in co

[anachronism]

Taper crimps are designed to keep the bullet from being pushed back into the case & still provide enough case mouth to headspace auto loading pistol bullets. Roll crimps are designed to keep the bullet from pulling out of the case & to slow the cases release of the pullet to allow chamber pressures to build to a higher level before the bullet is released.

[Char-Gar]

Use a good taper crimp die for the autopistol rounds.

Take a loaded factory round and with it in the shell holder at the top of the ram lift screw the TC die down as hard as you can just using your hand on the round and set the lock ring.

You will now produce rounds that will feed and fire well assuming you have done everything else correctly.

[August]

I've always believed that a seating die in auto pistol calibers is also a taper crimping die. In other words, that the die got smaller as you dropped it down further in the press. The directions that have come with die sets I've purchased have always explained this and the means for adjusting it. Am I in the correct orbit here?

[9.3X62AL]

Just my take on the issue--and I suspect I'm in the minority here--seating a lead boolit and taper crimping in the same die stroke will mar the boolit sidewall--sometimes deeply. Taper crimping of any lead bullet handload should be done as a distinct step, as per Mike in CO's recommendation.

If all you have is a roll-crimp seater die, all is not lost. Just follow the directions given by The Perfessor above, and you'll be fine. Taper-crimping of autopistol rounds is well-nigh superfluous in my view, unless as in the case of my RCBS 40 S&W/10mm die set--which only has a taper crimp seater die. My 32 ACP, 380 ACP, 9mm Para, and 45 ACP die sets all have roll crimp seater dies, and I have only bought taper crimp dies for the 9mm and 45. They largely go unused.

[35remington]

August, I believe you're correct. Generally, most auto pistol seating dies taper crimp rather than roll crimp if they're of reasonably new manufacture.

Some of the older 45 ACP dies, I do know, roll crimped.

Confirm with Lyman, please. You may also be able to look inside the seating die. See if there is a visible crimp shoulder as in, say, 38 Spl. dies. If not, you're likely holding a seating die that can taper crimp.

With lead bullets, it's best to taper crimp in a separate step to prevent plowing up lead in front of the case shoulder. You don't want to be squeezing the brass closed while the bullet is going into the case, especially if you're viciously taper crimping like so many guys think is proper. There's no reason to go below about .471" diameter at the case mouth after taper crimping.

Despite some ideas to the contrary, taper crimping doesn't do much to hold the bullet in the case under feeding forces. Bullet friction does that, not the taper crimp.

[theperfessor]

I have a lathe so I made M-type neck expander plugs in .38/.357, .41, .44, and .45 size. The smaller diameter of the plug gives the right neck tension, and the larger part gives about .002" clearance. I controlled the length so that when I run the larger diameter plug down in the case about 1/16" the end of the smaller diameter plug stops at the same depth as the bullet base at the normal OAL.

It makes it easy to set bullets straight in case, control neck tension, and create a further impediment to telescoping by having the base of the bullet rest on the unexpanded part of the case. It also minimizes neck splitting since you can't over-expand the neck, as well as minimizing the amount of crimp necessary.

[runfiverun]

hey al i have a 38 special taper crimp die, and it makes a swell neck sizer for my 358 win cases.
your 9mm might also.
the 30 carbine sizer die,works on my 308's pretty well too. like bushing dies.

[Harry]

I talked to the Lyman Tech. Here is his take on this:
If using jacketed bullets, and using the neck expanding die correctly, bullet tension should be sufficeint (no crimping necessary). If using cast bullets, the seperate taper crimp die should be used. Lyman does not recommend seating and crimping the cast bullet in the same operation. Seat bullet first, then taper crimp in a seperate operation.

[Echo]

I should have mentioned it in my previous post - I always crimp my auto pistol loads as a separate step, and recommend it.

[9.3X62AL]

LOTTA great info in this thread for new folks, guys. Man, I wish Cast Boolits had been around 25-30 years ago!