WHAT am I doing wrong? Seating die crumpling .357 Mag. cartridges

[Alk8944]

I just went upstairs to load a dozen .357 Magnum cartridges as I have been the .38 Special loads (and YES I have been readjusting the die accordingly and as instructed the same way with the .38s) The first load that I adjusted the die with came out just fine (which you see by itelf). Then the three that followed were crumpled in the middle like they were being bent inside the die. I then tried to take a fourth cartridge and started over using it as a starting point (as I had with the first one that came out alright) and IT was crumpled too.

It's a bit difficult to see in your photos, ones taken with a real camera would probably help, but it looks like the bullets are not seated to the cannelure. Is this correct? They look like the distance from the case mouth to cannelure distance varies, like the cases are collapsing before you even get to the crimp shoulder in the die.

I realize there is an often seen recommendation to use an expander that will give a lot of bullet pull without relying on the crimp, but, it can be overdone. If you are loading .357 bullets and your die has an expander that is .355 or smaller there is a terrific amount of friction between the case and bullet, sometimes enough to collapse the case behind the bullet, exactly like you seem to be experiencing. You can verify this by trying to seat a few without trying to crimp and see what happens.

Some .357 Magnum brass is quite thin relative to other bands, particularly Remington, so the sizer has to be small enough to adequately size the thin ones. These are particularly susceptable to collapsing as yours seem to be doing.

Try to find an expander stem that measures .356 or .357, with spring back in the brass you will have plenty of neck tension.

 

[BruceM]

I think that we've established that the problem is that the OP tried to crimp outside the cannelure-a NoNo. There is absolutely no reason why these should have to be done in separate bullet seating and crimping steps unless something is up with the crimp die. What is happening is a combination of too much crimp in the wrong place that is causing the cases to buckle- a fair accomplishment with a .357 case.

The OP should keep in mind that he should flare the case mouth just enough to start the bullet. Excessive flaring leads to neck splits in the not too distant future. As for the washers go, lets have the OP learn how things work before giving him the short cut.

I'll bet a dollar to a donut that the problem goes away once the bullet is seated correctly with regard to the cannelure. There is absolutely zero need for the post sizing of the loaded round with the FCD in this instance if everything is adjusted correctly in the first place. Using it is just an expedient crutch for flawed setup and/or technique.

".357's take a lot of crimp to prevent setback due to recoil." Actually, it's just the opposite in that the bullet is said to jump the crimp, not push (set) back into the case as in a bottom feeder round. What really happens when this "crimp jumping" takes place is that, during recoil, the bullet wants to stay in place while the case, primer & powder want to move backward-separating the bullet from the case. The cure for this is tight neck tension on the bullet plus a good crimp. The crimp portion of this is the last line of defense against crimp jumping, not the first. Therefore, the advice given relative to getting larger diameter expander, up to .357" in diameter is not good. You want the expander's diameter to be at least .002" smaller than the bullets diameter in order to insure good neck tension. The heavier the recoil of the round you're loading, the more important neck tension (bullet pull) is. In .41, .44 and larger magnums, you may need .003" lower than bullet diameter. It is more likely that a case will be bulged during expansion than during seating because of the difference in the co-effecient of friction between the bullet's jacket and that of the steel expander ball. There is even a greater disparity when comparing cast bullets to steel.



Bruce

 

[Neumann]

If you seat and crimp in separate operations, you can seat the bullet where you wish, crimp as much or as little as you wish, and never crumple cases or shave bullets. It doesn't matter if there are minor differences in case length. It is a simple solution to a perplexing problem. That's how every progressive press works and that's how it works for me.

It is very simple to set the OAL - Keep an unprimed, unloaded cartridge for use as a gauge, and set the depth by feel. If you need to make fine adjustments, 1/8 of a turn of the seating post is approximately 0.001". It takes less time to execute than to read this paragraph.

The only reason to combine these operations is to save time in a single-position press. For that, you pay a heavy price.

 

[Doug.38PR]

well, I readjusted the die, doing it as the lee video says, (I have an RKBS btw) doing just what I did before only backing it out 3 full turns intead of 1/2 a turn. Long story short...it works now. Seated and crimped just fine now.
Thank y'all for all the input!

 

[Paul5388]

I've been loading .38/357 since 1968 and used RCBS dies that seat and crimp in one step. Never had a problem when it's set the way it's supposed to be set.

 

[Skip Sackett]

well, I readjusted the die, doing it as the lee video says, (I have an RKBS btw) doing just what I did before only backing it out 3 full turns intead of 1/2 a turn. Long story short...it works now. Seated and crimped just fine now.
Thank y'all for all the input!

Very good. Can you show us a picture of a finished round now?
Understanding HOW the die works will really help in the future when you go back and forth from 38 to 357 too.

Glad we could help.

p.s. While all of the dies are made a little different, the types (seating/crimping, flaring, sizing) all pretty much work the exact same way. Just for info.

 

[jwr0201]

crimp separately

If you are using Lee carbide dies, crimp as a separate process. Lee's FCD is very easily controlled in small increments. Use a magnifying glass to look at what the crimp is doing and gradually go from light to heavier. Also, make dummy test rounds to get all of your dies set. Record the data and you can always go back to your previous settings by using the successful dummy 'model' rounds that worked.
Personally, I decided not to mess with having to adjust from 38 to 357 mag and back - just got another set of carbide dies. Once I set my dies for the rounds I like, they stay at either 38 or 357. Only minor changes are needed when changing bullet types - staying with the same dies set for the particular caliber. Good luck - this is actually a good learning experience, which everyone has!
RR

 

[Jeff423]

Experience is something you get right after you need it.

Jeff