Bulging .380 cases while expanding

C

Carmady

New member
I was reloading (single stage) a bunch of .380 range pickups and noticed during the charging/seating stage some cases were bulged in the center (before charging/seating). I put the bad ones aside and ran them through the resizing die a few times to straighten them out. That worked fine. Then I went to expand them (again) and noticed that they were bulging again.

I checked the brands of the brass, the the offenders were labeled Speer, S&B, and Perfecta.

The DL;DR version:
Speer, S&B, and Perfecta .380 brass bulging during the expanding stage.

There was a LCP barrel handy, and they didn't want to chamber with mild finger pressure.

This was a new one to me. Was it because of a thinner case wall thickness collapsing while going up into the expander die/plug?

Federal and Winchester brass was issue free as always.
 
If you look at this drawing of a .45 ACP cutaway, you'll notice the case walls get thicker about 0.35 inches below the case mouth, so that's the maximum depth to which a bullet may be seated or an expander may be pushed without bulging the case as you describe. It sounds to me like the offending cases just have that thicker portion starting higher up than your well-behaved cased do. You could section a few to look, but dropping a pin gauge in to find it would be faster, if you have a set.

One way to handle this, other than dumping the brass, is with a universal expander, like the one Lee makes. I usually use something like the Lyman Multi-expander, but you have to be sure the insert that does the expanding isn't too long for the job. It might mean shortening it with a Dremel cutoff wheel and re-rounding and polishing the edges to get it working properly for you. Keep in mind, though, you can't seat standard flat-base bullets any deeper than that thick area, either, so if your bullets are not happy seated in the space allowed in the case, they aren't any use to you anyway.

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Thanks for the detailed explanation.

I noticed when back at the press that it was a matter of the walls being thicker and hugging the expander plug , rather than the walls being too thin and ballooning out. The Speer cases acted like they hit a concrete wall, and I didn't try to force them in. It was only 15-20 cases, so I just threw them away.
 
There have also been some oddball cases from the other side of the pond in 9 mm that were very thick brass with an almost drilled out looking recess above the flash hole. Lot of brass in them. All I could figure was they were for some kind of reduced target load for which they didn't want the reduced powder charge to have too much empty space around it. Probably reduced the charge needed and improved velocity consistency at the same time.

In your case, I don't know why Speer would have the brass run that way, but you can call and ask them. Vista Outdoors, which owns them and several other firearms industry companies, has a sort of central tech number you can call and they'll connect you with a Speer tech.

What make is your expander die?
 
Ah, well, you may be in luck, then. Call RCBS Customer Service at (800) 379-1732. Explain the problem. Ask if you can send them the expander with a couple of the problem cases and have them fix it to work with them. They often do customer service things without charge.
 
The odds are that your expander is going into the case too far and hitting the web. If you use jacketed bullets, you might be able to use a case mouth flare-only tool (like the Lee Universal Expander, that doesn't expand at all and just flares), but it won't work well with plated or lead bullets.
Be sure that you have a .380 expander and you're not using a 9mm expander. Then, contact the die company and explain your problem.
 
As already described, he's hitting the part of the body wall where it thickens in these auto pistol cases. It's not going all the way to the web or the die would have stopped the press ram from being raised all the way and the Federal and Winchester brass would have been a problem, too. The web is, by definition (see free glossary on the SAAMI site) the non-flash hole part of the brass separating the floor of the primer pocket from the inside of the head at the bottom of the powder space, though many, including many gunwriters, misuse it to mean the whole head between the outside face and the bottom of the powder space inside the case.
 
I've been plagued by that same problem when reloading that little case. Success was a matter of persistence and trial & error. I've been thinking about looking into the Lee universal expander.
 
Got the same problem. I use a lyman m-die expander with better results than the expander that came with my rcbs set. Ill try the lee universal expander but i dont anticipate much better results as i use plated or lead bullets
 
One thing to keep in mind about the SAAMI drawings is they only address the outside dimensions of the case plus the primer pocket. The individual brass maker gets to do what he wants with the inside, and that's where the difference is coming from here.

The main advantage of the M-die over the Lee universal die is it will put that little step inside the case mouth that makes it easy to seat the bullet straight upright and have it stay in place all the way into the die. You get less bullet tilt and you don't have to keep your fingers around the bullet until it starts into the die.

The Lee die is just a conical taper. Works as well as any tapered flare, but no better. The advantage in this instance would be that it doesn't try to expand the case below the mouth, either, so that part won't come into the equation.
 
joeanybody said:
Got the same problem. I use a lyman m-die expander with better results than the expander that came with my rcbs set. Ill try the lee universal expander but i dont anticipate much better results as i use plated or lead bullets
Click to expand...
I use only Lee dies, for .45 ACP, 9mm, .380 ACP, .38 Special, and (recently) .44 Colt. For .45 ACP and 9mm, I load Berry's plated bullets, and I've never had a problem or found a need for a true expander.
 
You have to be looking at target shooting accuracy or leading problems to see the benefit.

A way to see the signature of the problem is by examining your finished reloads. When the bullet is seated it expands the resized brass. Most modern carbide handgun cartridge sizing rings tend to make cases fairly straight, whether they are designed to be straight, like a revolver cartridge case, or they are meant to have a taper, like a 9 mm auto case. As a result, the case is wider over the bullet than it is below it. This creates a slight shoulder on the outside of the case that mirrors the location of the bottom end of the seated bullet's bearing surface.

Using the tapered-only or belling-only type expanders and especially when using bullets with short bearing surfaces, you often see that shoulder ring mirroring the bullet base does not go evenly around the case neck region. It is not uncommon for it to show only on one side and not the other. It is the result of the bullet being slightly tipped in the case instead of straight in. If it is straight, you see the ring is fairly even. It may not be perfect, due to variation in case neck wall thickness, but you can clearly see it all the way around.

My Dillon Square Deal used to produce .45 Auto rounds where the location of the bullet base often only appeared on one side of the case. But I used my lathe to grind the Lyman M Die type profile into its power drop/operating tube and created that little step (and I had to shorten the end of the expanding portion an equal amount. I now set bullets upright in the little step it creates in the brass neck, and now I always see the bullet base mirrored all the way around the cases. This practice also shrank my 50 yard groups about 15%, though the gun was shooting just under 2 moa at 50 yards at that time, making it easier to see an improvement than it would be now, when it is shooting closer to 4 moa at 50 yards (it's been years since I last tightened it up). Leading no long builds up significantly in that gun at all.

There are other ways to make this happen. A friend of mine with a Dillon 1050 decided to stay with 200 H&G 68 nose profile bullets, so I turned him a seater plug that matches that nose contour very closely. His bullets are on a standard Dillon expander bell, but the seater plug now pulls them into straight alignment before they start to seat. The benefits are the same.
 
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