Crimping with Lee dies

[rd2play]

OK, more questions, in less than 24 hours...

Based on what I read here revolvers generally need a roll crimp and pistols a taper crimp.

My question is: how do you achieve those different types of crimps with Lee's die set? Is it capable of that?

The other question: the four-piece Lee die set includes their "Factory crimp die". I understand that it's a dedicated die for crimping. What's the difference though between crimping with this new die versus using a properly set bullet seat die? Thank you.


EDIT: and what does this actually do http://www.buffaloarms.com/Detail.as...57407&CAT=3872 ? Creates a cannelure on a bullet without one?

[rd2play]

OK, I just read that apparently the 38/357 Lee die is set to create a roll crimp automatically, while their 45ACP die does a taper crimp.

I'm still wondering though what advantages the factory crimp die offers over the bullet seat die.

[Bill Steele]

The only difference with a separate crimp die is you crimp the bullet while it is not moving. When you crimp with a seater die, the bullet is moving to some degree as the crimp comes down. Generally, if properly adjusted a seater die will work fine. Separate crimp dies are much easier to set up properly and they crimp while the bullet is already fully seated. In some cases, a seater die will not have a crimp function and if you want a crimp, you have to use a separate crimp die.

The roll crimp is for rounds that headspace on the rim of the case (or a shoulder) and use a bullet with a cannelure. The dies for a given caliber usually (not always) come with the proper crimp. In some cases, if you crimp down far enough with your "taper crimp" die, it will put a crimp on that look like a roll crimp. It really depends on the design of the crimp portion of the die. Some taper crimp dies have a pretty sharp taper, others are more gradual. Roll crimps always have a pretty shape ledge that applies the roll crimp on the case.

In addition, you don't "have" to roll crimp a round that calls for one. Many people load revolver rounds using only a taper crimp. It all depends on what you are trying to accomplish, how much and what type of powder, etc.

In the case of a round that headspaces on the case mouth, a taper crimp is the only way you want to do it (generally, basically just taking the belling out of the case).

I hope all the foregoing rambling makes sense.

[rd2play]

I hope all the foregoing rambling makes sense.

It does make sense. I appreciate it.



Based on what it says here, it looks like the Lee crimping dies do only taper. And then they offer a taper crimping die for 38 Special. Shouldn't they offer a roll crimping die instead I guess I should contact them to find out more.

I realize that probably most people reloading 38 Special use the die that Lee ships and have absolutely no problems. I'm just trying to figure out more for my own education.

[Bill Steele]

The die in your link is a taper crimp die.

The dies that come in the .38/.357 caliber set have roll crimps. If you get the deluxe die set (with the FCD), the seater will have a roll crimp in it (you just need to screw it in far enough to use it) and the FCD will have a roll crimp as well.

If you use the separate FCD, you just screw the seater into the press far enough to use the adjustable seater porition and not have the crimp come down on your brass. After you get the dies and look up inside each of them, this will all make sense.

[Clownpuncher]

The purpose of the roll crimp is to ensure that the bullet doesn't set back or pop out from the recoil of revolvers where the round is headspaced with the rim of the case. Semi auto uses the rim of the case to headspace so you must use a taper crimp otherwise the rim of the case would be turned over into the bullet and you would not be able to properly headspace.
So, since a 38/357 round is headspaced by the case, you can use either crimp. Typically, if there is a cannelure on a bullet you roll crimp it but you don't have to, you can still taper it. Lately I have been using Berrys plated bullets for 357. They do not have a cannelure so I use a taper crimp. They have been working flawlessly and my gun stays cleaner too.
The big thing I do when setting up the die is after seating and crimping a bullet, I give it a good push on the bench to make sure it isn't moving and then I take the bullet out using a bullet puller and make sure I haven't squeezed the bullet so hard that I have deformed it or used too much crimp.

You can do the same thing with your bullet seating/crimping die, just set it so light that is is essentially a taper crimp and then check it like I outlines above. Set your crimp first then screw in your seating plug after you have the crimp you want in order to get your OAL.