As a new reloader trying to get a feel for how much crimp constitutes a light crimp vs. a heavy crimp, I was wondering if there is a good rule of thumb for how many turns of the die it takes to obtain a consistent light, medium, or heavy crimp with 38/357 loads after the seating die first makes contact with a resized case. For example, after the die makes contact with the brass, lower the ram and turn the die x turns for a light crimp, y turns for a medium crimp, and z turns for a heavy crimp.

Turn it in a small amount and see if it's what you want, if not turn it in a little more and so on until your happy.

Remember to back out your seater plug while doing this so as to not seat the bullet any deeper.

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John

What I think I want/need at the moment is a medium crimp for a 158 grain cast lswc. Regardless, the Hornady manual I have on hand does not go into detail on this topic and I haven't found any guidance online (pictures would be useful) that I thought I could trust, so I was hoping it was as simple as a repeatable and predictable process. It should be, shouldn't it? ... well, at least insofar as we are generalizing with baseline terms such as "light" and "heavy".

I understand that a little more or less crimp will be needed for any given load depending on the specific powder and charge, among other factors. And presumably getting a feel for the ideal "more or less" crimp needed is something that can only be learned over time. It would be really convenient if I could just step outside and shoot a couple cylinders for testing purposes. Unfortunately, that's not the case.

I understand the basic process of seating and how to crimp on my single stage press. What I'm really looking for is general guidance on what constitutes a light crimp, a medium crimp, and a heavy crimp. If anyone has any pictures for general illustration purposes or can point to a good resource online or otherwise that clarifies the various crimps, I'd appreciate it.

Look at factory rounds in the calibers your loading, try to duplicate them.

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John

That's a great idea – at least for jacketed ammo. The lasercast lswc bullets I am using have a much deeper crimping groove than, e.g. XTPs. Wouldn't the crimp look a little different for a lswc than with a jacketed bullet?

Crimp into the crimp grove, the tighter crimp you make, the faster your cases will split and wear out.
All you want to do is keep the bullet from seating deeper, or jump foward under recoil.

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John

With a roll crimp, a heavy crimp is when the case mouth edges touch the bottom of the crimping cannelure. A light crimp would be just enough to close the bellmouth - medium, case mouth edges just entering cannelure. This is just how I think about case crimping, and it's likely to be pretty subjective. The upside here is that you get to load and shoot hundreds of rounds of differing configurations to find out what your gun likes !

Larry

Read the instructions that were with your dies, there is lots of useful information and tips in them. Typically you'll find that 1/2 turn of the die can be the difference between a light crimp and a heavy crimp. In addition with the revolver calibers you may find that you'll need to trim your cases to length to avoid having some of the longer cases buckle. It's why I don't use a combined seat/crimp setup for my 38 special and 357 Magnum loads.

Reading your reloading books and instructions that came with the various tools is the way to go. I've never trimmed a .38/.357 case in 35 yrs of reloading. Crimp the case until it holds the bullet in place, the lightest crimp that will work for you is the one you should use. I would be more concerned about proper powder loads than worrying about a heavy, medium or light crimp. If you know an experienced reloader in your area, ask to look at his cartridges.

You will not need "Turns".

With my die on a 38 Special ..........

a light crimp to a heavy crimp, all takes place in 1/3 of a turn on my die.

Good luck.

It's something you are going to have to do trial and error style to get the hang of. There are no specific amount of turns. I seat my bullet to the depth desired, then crimp in a separate step. I turn the crimp die down untill it touches the case, turn it in 1/8 turn at a time, looking at the crimp at every adjustment , until I get the crimp I want. Applying more crimp is easy, go too far, the case bulges and you have to pull the bullet and start over.
It's easier to adjust the crimp with the bullet already seated to the correct depth. Going from light crimp , to heavy crimp , to bulged case- too much crimp, will only take a fraction of a turn.
So use fractions of a turn and keep a close eye on how much of a turn affects the crimp...pretty soon you will have it all down.

Gary

Yes, the crimp will look much different. The lead bullet has a groove and the XTP has a crimp line. The lead bullet the case mouth folds into the groove, on the XTP in also folds but not as far as it is held by the perforations You can actually crimp it so much it will indent the bullet which you do not need to do.

I use Lee dies but the principle may be the same with yours. With a properly sized and flared case in the press, screw down the die until it hits the top of the brass. It is now at zero crimp. tighten the lock ring a bit. Back out the seating knob on top. Place a bullet and seat it to just a little longer than you want it to be (.05") Now seat the bullet. There should be no crimp. Make a mark with a marker on the die body and turn the whole die body a half a turn. Now raise the ram, did it crimp a little? want more? turn the body in another 1/4 or so and crimp again. Should be crimped now. That is why you leave the bullet a little long as when you turn the die body it will tend to seat the bullet a little bit and drive you nuts. Tighten you lock ring.

At least that is how my dies work.

Here is a 45 Colt crimped Guess you would say heavy but I crimp them all the same, there is no light crimp for these. It is crimped into the groove.

Some 357 show the difference of non trimmed brass, same crimp on all.

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Still Running Against the Wind

What I did and will still do as I'm new to reloading as well is seat and crimp bullets into empty and unprimed cases. Then when I get the crimp I want I either keep it for a reference for next time or remove bullet and reuse them.
I don't mine sacrificing a few cases or bullets to get the crimp that I want.

I finally learned to move the die in 1/4" turns for course adjustments and 1/8" turns for fine tuning.

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"He was kinda funny lookin'"

Less is more... too much and you can start to crush cases as well..

+! on post #13.....

Nothing like a "Dummy round" in a empty case to keep in your
Die box or the box of bullets that is "Perfect" for the OAL and crimp that is needed for a load.

Sure saves a lot of time.

That goes along with my being too heavy handed. Ruined some good cases before I finally realized that easy does it.

I can't remember what it is called, but saw an article advocating a crimp that instead of rolling into the groove, flattens into it. I don't know why anyone would want to do this. I call that being way to hard on case mouths. it's probably like a lot of poorly thought out fads that not only should not have caught on, but never should have been introduced in the first place.

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"He was kinda funny lookin'"

Wow, thanks everyone! That's a lot of useful information on crimping. Hopefully some of it sinks in

That description makes sense.

Do you use a separate, dedicated crimping die or seat and crimp in separate steps on the same die?

I was afraid of that, but I had to ask...

I have some reloads with a very slight bulge around the seated bullet, although the bullets in question all chamber easily in the cylinder. Is a bulge this slight cause for concern? Is the bulge the result of both incorrect sizing (case too narrow) and too much crimp or just too much crimp?

A picture is worth a 1000 words. Thanks!

Good tip! And a worthy sacrifice of a few bullets and cases.