357 Magnum Creep

I wish I had seen this thread before you ordered your FCD. In my opinion, the Lee collet style crimper (not the FCD) is the only way to go for 357mag. It does not depend on consistent trim length, and it won't try to resize the case (and possibly swage bullets smaller). You can even crimp with plated bullets that don't have a cannelure as it will not break the plating.

9mmepiphany said:

To get optimal neck tension, I size with a Redding Carbide Dual Ring Sizer and expand with Redding's M-profile Expander

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That's what I use except Lyman M-die, that combo just plain works. I test my neck tension with a strain gauge and those Redding Dual Ring dies make a lot of neck tension and after their loaded, they look like factory ammo.
The neck tension was the best surprise when I bought mine.
These rounds are taper crimped and are over 65Lbs of neck tension from my Shimpo strain gauge. My stain gauge pushes the bullet down and, without the coke bottle effect from standard resizing dies helping to hold the bullet from moving, I am still getting this kind of neck tension with only a taper crimp.

I would think the expander would affect the neck tension more than the sizing die, unless the expander isn’t going as deep as the bullet.

9mmepiphany said:

I don't think I've ever seen a case where the expander was set to go further into the case than the bullet does when seated.

With a M-profile expansion die, the plug creates a "seat" for the base of the bullet. Most of the bullet remains above the case mouth. If an expanding plug went into the case further than the bullet when seated, wouldn't the bullet fall into the case when placed at the case mouth?

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No, the expander sets the inside diameter to be slightly less than the diameter of the bullet, usually about .002-.003”.

Shak3s1977 said:

I honestly think it's the Dillon dies. It says they start as a taper crimp and if you keep increasing the crimp, it makes a roll crimp. Not sure about that.

So far I haven't been really impressed with my 44 magnum Dillon dies. I have got the crimp die cranked down pretty good to keep my 44 bullets from crimp jumping due to recoil. Using Lee dies in 357 magnum, I have no problem.

I've got lots of Dillon dies and for semi-auto rounds I think they are great. For sizing and seating, I think they are pretty good ( though I do like the fine adjustments of other seating dies better). As for their crimp dies, I have no problems with their taper crimp dies. For roll crimping my 44's, I'm going to switch to either a Lee Crimp die or a RCBS roll crimp die.

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I use Lee Dies exclusively even on my Dillon 650. I only load 38spl and 9mm on the Dillon press and fought the Dillon Dies for about an hour and switched to Lee and all problems solved. Did leave the Dillon expander/powder drop die. I use a Lee Classic Turret for 357mag, 44mag/spl and 45acp all with Lee Dies. I do have a RCBS Roll Crimp die for .357 that will put a nicer looking roll crimp than the Lee FCD but hardly ever use it. Been loading for 40+ years and never trimmed one piece of handgun brass and I'll get a short case here and there that you can tell when crimping. It has little resistance. I just pull those out and when I'm done with a run, crank the die down a little and get them too.

Toprudder said:

I would think the expander would affect the neck tension more than the sizing die, unless the expander isn’t going as deep as the bullet.

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You would think so but to get the step in the case to seat the bullet it has to be going in the case deep enough. I bought this M-die with the dual ring Redding resizing die at the same time and that combo is making that neck tension on my .357 mags.
I suppose it's possible that the M-die is on the small size of what neck sizer should neck size at. It says 38F or P or something on the end of the knob, so I know I'm not using my 9mm M-die to get this kind of tension and the necks aren't splitting on my cases. My 9mm M-die never leaves my LNL-AP anyways.

The Redding dual ring die resizes the necks down to a full .001" more than my RCBS die does, but resizes the body down much less than my RCBS single ring die does.
The Redding Dual Ring Die resizes the inside of the necks to .351"

My M-die measures .355" but resizes the necks on my Starline brass to .353" due to spring back.

My bullets are .357-.358. That's .004 to .005" interference fit depending on jacketed bullets vs plated bullets. I've had one split .357 mag case in the last 10 years. Some of my cases are old Winchester cases from back in the late '80s.
This process works for me so I'm not messing with it but I do suspect I'm getting and extra .001 of press fit with these two dies. edit: over what may be considered normal.

Regarding the dual-ring dies from Redding, I do the same thing with a poor-man's method. I use a Lee FCD without the crimp insert to full-length resize the case, and then follow up with the normal resizing die, but only size the seated bullet area of the case.

Expanders are definitely different sizes and shapes. The rcbs cowboy expanders are said to be larger just for cast bullets. The m die that gets a lot of love has two effective diameters. This data set may be a fun time killer for the winter.

for fast and heavy bullets, i use a 9mm sizing die after the 357mag/38spl die to size the case (just enough to get past bullet seating depth) a bit more so my custom (rcbs made it for 35 dollars) .354" expander die has something to expand. this combo gets me to a .004" neck tension.

luck,

murf

Keith Wygal said:

Thank you! I appreciate the tip! I figured this might be the case. I just ordered Lee Factory Crimp die and a case trimmer from Midway. So good thing I didn’t start reloading to save money...lol. I wanted to because I thought it would be fun... and I was right I really do enjoy it. And even with the set backs I think of it more as a challenge.

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The proper way for a new reloader to find this issue is to load 500 rounds... THEN discover the issue... so you have 500 rounds that you have to pull before fixing the problem... Well, that is the way I did it when I was new to reloading at least!

I have Dillon Dies for .308, .223 and 9mm. The .308 and .223 carbide sizing dies are GREAT! I didn't find anything special enough about the Dillon 9mm die set to buy any more Dillon dies. I do have Lee factory crimp dies for pretty much every one of the dozen calibers I reload for. I am a big fan of the Lee collet crimp dies!