RCBS 38/357 die problem


March 21, 2008, 09:36 PM
I have the RCBS 3-die 38/357 set, and am running them in a Dillon 450. Setup was IAW instructions, and all went well, based on appearance. After having made a handful of rounds today, I noticed that the round looks "swollen" where the bullet is seated, and, despite my crimp, they will not fit in a 357 cylinder. For every other pistol round I load, I use a Lee FCD, and that solves the problem. Do I need to add the FCD to my current cycle, or do I have something improperly adjusted?

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Steve in PA
March 21, 2008, 09:47 PM
Must have something improperly adjusted. I've been reloading .38/.357 (plus otherr calibers) for over 18 years now with the same set of RCBS dies. Not problems or issues.

Sounds like you have too much crimp.

March 21, 2008, 09:53 PM
Thanks for the reply Steve in PA.

Would too much crimp cause it to swell that bad? If I run my fingers along the case, I can feel where the bullet has made the case "fatter". I think a FCD would solve this, but I'd rather fix the issue than correct it.

Grandpa Shooter
March 21, 2008, 11:39 PM
You haven't told us what the bullet diameter is. The correct diameter is .001 over the diameter of the bore of your gun. Have you checked the diameter of the bullets you are using? I buy ones which are .358 at the base. I have gotten some at times where the mold had eroded and the bullets were .0005 over and some were .0002 over. Depending on your barrel a bullet which is .3585 or .359 will likely bulge the bullet as you describe.

Check the diameter and let us know.

March 21, 2008, 11:49 PM
Cast and rapid cooled out of wheel weights to .358. When I cast 40 and 9 bullets, I don't have this issue, as these guys run through a Lee FCD after seating.

To make sure I'm not missing something, the RCBS dies don't size the bullet to any degree after seating and crimping, correct?

Steve C
March 22, 2008, 01:44 AM
The RCBS dies come with an expander (like most dies) with a diameter that's good for jacketed bullets and depending upon the brass thickness will work OK for cast bullets. I personally like to use Remington brass for reloading cast bullets as its a bit thinner and doesn't bulge the cases. If I don't have Remington brass available I can avoid the bulging by hand starting the bullet in the case a little deeper and going slow seating the bullet. While this works fine on a single stage it kind of defeats the purpose of a progressive.

If you are loading a lot of lead getting a .001" larger diameter expander should solve your problems if you don't want to make the adjustment using thinner brass. You can contact RCBS via their website or telephone help line and see what they can do for you.

March 22, 2008, 08:55 AM
I'm using a Dillon 450, which uses it's own expander in conjunction with the powder drop. I tried adjusting the amount that I expand, and am seeing similar results both ways. I have a sneaking suspicion that this is a sign from the reloading gods telling me that I need to go buy a FCD and be done with it.

March 22, 2008, 09:43 AM
You did not say whether you sized your bullets after casting.

I believe that is the source of your problems, your bullets are too large of diameter.

Ol` Joe
March 22, 2008, 09:49 AM
The RCBS sizer is sizing the case ID down below the bullet diameter as do all sizing dies. The rifle die sets have a expander ball to reopen the mouth to about 0.003" below bullet diameter but straight wall sizers don`t expand the case back out they leave that to the bullet and just "bell" the mouth to help with starting. The bullet is expanding the case walls out as it is seated and the expanding stops at the base of the bullet, this is what you are seeing. This is normal in most cases and nothing to worry about, it also is the source of most of the "grip" on the bullet, not the crimp. The thickness of the brass will make a difference in how small the ID of the case is when sized and older work hardened brass will not resize down as well as newer cases. I`d expect you have over crimped the case and bulged it more just behind the mouth and this is most of your problem.
The Lee FCD does size the whole cartridge, bullet and brass, when crimping. Some like this, some don`t, I personally don`t feel it`s needed but,............

March 22, 2008, 11:59 AM
it sounds as if your over crimpin the mouths of the cases & causing a bulged case .
is it on all rnds ??
have cases been trimmed ??
to get consistent crimps they have to be the same length.
ive bought factory stuff that varied .o22 & that`s alot when adjustin the crimp!!!!
some loadings i seat & crimp in seperate steps also .
hope this helps ,even if a little .
reread your post & wanted to add: are you using a bullet that has a crimpin groove ??
if not ,such as rainers or berry`s by the time you get a (crimp) you`ve applied enuff pressure to bulge the case & also most likely cut the plating .don`t ask how i know!!


March 22, 2008, 12:00 PM
I"ve been using RCBS in that caliber for years with no need for the FCD die.
Sure sounds like the bullets are the problem..or thick case walls on the brass.

March 22, 2008, 12:58 PM
If they swell the cases until they won't fit in the cylinder, the bullets are too big.

Have you actually measured them at .358"?
Measured lots of them, or just one?

If you are just going by what the mold manufacture says it does, it is probably nowhere near .358".

Just changing the alloy mixture will change the bullet diameter of a cast bullet.
That's why they need to be sized after casting them.


March 22, 2008, 01:45 PM
Reset your crimping/seating die. Yours is bulging the case. Your trying to push the bullet in while the crimp is in place, this crumples the case just enough to cause loading problems. You want to seat the bullet then crimp.
I'm guessing about a half turn out with the die and a quarter turn in with the seater plug.
I have had this problem before. I thought it was bullets, brass etc.
Its a simple readjustment.

March 22, 2008, 01:51 PM
Do I need to add the FCD to my current cycle, or do I have something improperly adjusted?Is the bulge up near the crimp, or at the base of the bullet near the middle of the case?

Near the crimp is too much crimp.

Near the middle somewhat normal until it gets too big to chamber.
That is caused by too big a bullet diameter.

Can you post a picture so we know what we are guessing about?


March 22, 2008, 04:16 PM
I was assuming that it was the girth of the case where the bullet is contained (it's visible from the outside), but it turned out to be the crimp itself. I tried not crimping and the rounds I made seated in the cylinder just fine. So, I went back and reduced my crimp... all is well now.

All of my experience has been with Lee, and this being my first time with RCBS dies, there were bound to be stumbling blocks. I ran the first rounds I made through a FCD and now they work as well.

Thanks for your help everyone!

Edit: "Bulge" is the wrong term here, it's more of a visible expansion where the round is seated. A picture would have solved this. :)

Steve C
March 22, 2008, 05:19 PM
but straight wall sizers don`t expand the case back out they leave that to the bullet and just "bell" the mouth to help with starting.
This is incorrect, there is an expanding portion of the die stem, that's why it is called the expanding/belling die not just "belling". Here is a picture of the RCBS .357/.38 expanding and belling stem from that die, note the 2 portions of wear, the first portion expanding the case to proper dimension to hold the bullet and the belling portion that actually bells the case mouth. It's been common for cast bullet users to get a larger diameter expander plug from RCBS for cast bullets. The part that is larger in diameter is the "expander" portion of the plug not the flaring portion.

March 22, 2008, 05:27 PM
I just bent the decapping pin, so I have a very simple solution. If anyone wants a free set of RCBS 38/357 dies (with a bent decapping pin), all you have to do is pay shipping. Dead serious, first taker gets 'em.

Edit: included are a couple extra seating pins (for FN, RN and WC). If I don't get a response soon, this is going in the PIF thread. Thanks!

Dumpster Baby
March 22, 2008, 06:31 PM
I'll take them! I want to have a set of RCBS dies set up for .357 and for .38 Special so I don't have to readjust them back and forth. Let me know how you want to do this.


March 22, 2008, 06:37 PM
PM me your address, I'll send them out Monday. And if you would, be a dear, and send a check or MO for the shipping cost to my return address. Best of luck, I'll stick to Lee.

Everyone else, thanks for your help.

Dumpster Baby
March 22, 2008, 06:50 PM
PM sent.

March 24, 2008, 05:33 PM
Dies sent. Lee for me!


Master Blaster
March 24, 2008, 06:28 PM
Back the die body out 1/4 turn, and screw the seater in 1/8, repeat until you get a nice roll crimp and no bulge.


March 24, 2008, 07:03 PM
Listen to GP100Man. He told you everything that was causing it and how to fix it.

March 24, 2008, 07:56 PM
You can bulge .38 Special cases by seating the bullet too deep. At least I can.

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