Case bulge

I was running some 9mm cases through the expanded die. They were already primed. 9 out of 300 had noticeable bulges
just below where the die would have been. Also they took more pressure the run through the die than the other cases. Resized them, and popped the primers. I ran the cases back through the exp die, no bulge and no effort. Could the die have been so tight the air couldn't escape and caused the bulge. With the primers out no problem. Been loading for quite awhile but not 9mm much till recently.( nice to be senior instructor with key to ammo locker) Before I had Lee dies which had a hole in the top. I now have RCBS which doesn't. Talked to a friend who loads everything from 223 to 450/500 Martini and he had no idea either. He loads 9mm and never had that problem but has Lee. My possible cause for the problem sounds a little far out, but can't come up with anything else. Anyone have an idea?

tight expand plug and good neck tension sure could bulge your brass.

What happens if you expand real slow, give it a little time to equalize internal pressure.

I'd just go with deprimed brass.

I always resize and deprime. Then expand and then prime fully processed brass. Never an issue.

Why would you prime, unprocessed brass ?

prime

Nevada Ed said:

Why would you prime, unprocessed brass ?

Click to expand...

I size first. Whether I prime or exp after that depends on what I'm doing. I can watch TV and with my lee autoprime 3-400 cases while watching. You can make a mistake with the old autoprime but you have to work at it. If wife is in a talking mood I go in the gun room and exp.

Houlton said:

I was running some 9mm cases through the expanded die. They were already primed.

Click to expand...

I do not fully understand, as Nevada mentioned??

The sizing die normally sizes and deprimes in one stroke. To size primed brass that is not sized makes no sense? You would have to have the deprimer pin removed also.

Now lots of folks will size and deprime then prime and leave them for later loading with powder and a bullet.

Batch loading you can resize and deprime all your brass, then sit and watch TV and chat or whatever while you hand prime. Then Flare your brass while charging powder and seat and crimp bullet.

So again this is all convoluted, unless I am missing what you are saying??

Where did you get your brass? Was it new, primed brass? Was it range brass that someone else primed before you got it? If it was pre-processed range brass, you might have gotten hold of some brass that had been shot in an older Glock, one with a chamber that didn't fully support the cartridge. Does the bulge look like the "Glock bulge?

9mm Glocks are pretty well supported so they do not bulge like the 40 SW used to. I think the OP issue is different.

Heck my 9mm SW Shield with hot loads will bulge brass

Lee bulge buster

I have the lee bulge buster for 40 cal they say you can use a 9mm Makarov crimping die to put 9mm's through but never tried it,
I heard the 9mm cases are tapered don't know for sure

Probably wasn't clear. I had 300 sized ,primed cases. When I ran them through the exp die 9 out or 300 bulged. The ones that bulged were very tight in the die. The rest went easily.I ran them back through the sizer die to take out the bulge. I didn't take the rod out so it popped the primer. When I ran the cases back through the exp die I hadn't reprimed yet and this time they went through very easily with no bulge.

Recommended process:

1. Size/deprime

2. Expand

3. Prime

4. Load powder

5. Crimp/remove flare

Do it the same way every time.

A die that isn't...

A die that isn't open to outside air should have a vent hole.

Maybe I am confused with your terminology

For LEE dies

The sizing and depriming die is one die

The EXPANDER die, is the powder through die. By expanding, that is simply the flairing of the case mouth.

So that said did you cases not have a bulge and then when you FLARED them that created the bulge?? If it did then you need to re adjust you POWDER through Die as it may be screwed down to far and you are over flaring (the odd cases may be a tad longer but I doubt that is a issue)

The amount of expansion or flair should be so small that a bullet just barely will start.

Other than that I am at a loss as to what is going on

Hand Gun Dies - Lee Precision

I understand your process. It's not what I do but what do I know?
Did the cases have some type of sealant inside the case mouth? That would cause your expander to bulge the case.

Well!

Make sure that you have the die pushing the shell holder a little.
Some call it a bump. Don't expand the case mouth anymore than you have to insert the bullet.

When using range brass there will be a delta in the amount that the brass expands. Glock brass will be larger than almost any other! Good luck with your quest.

NJM15 said:

I have the lee bulge buster for 40 cal they say you can use a 9mm Makarov crimping die to put 9mm's through but never tried it,
I heard the 9mm cases are tapered don't know for sure

Click to expand...

Yes, you can run 9mm through the 9mm Makarov and it works GREAT.
I check all my 9mm with a gauge, and about 5% won't drop. I put the fails through the Makarov and it fixes them all.

Houlton said:

Could the die have been so tight the air couldn't escape and caused the bulge... With the primers out no problem... I now have RCBS which doesn't.

Click to expand...

I have RCBS 9mm dies & I've done many hundreds & have not had that problem. Not sure what was going on there.

I've always sized/deprimed, then I prime all the cases. (I do both of these on the bench mounted JR3 press in the garage.)

I expand/flare the cases only once I'm ready to start loading on my portable reloading table inside with a turret press. Since I'm usually loading a mix of different bullets (styles/brands, jacketed/cast), I expand the cases for each particular one just enough to start it seating. Cast always need more flare than rounded base plated bullets & sharply cornered jacketed bullets need a different setting. That's my logic anyway for doing it in this sequence.

.

Seems there is a misunderstanding on your process sequence. Juts to insure clarity the way I'm reading it you are

1) Sizing and depriming.

2) Priming the cases.

3) Flaring the case mouth.

So, can gas pressure cause an unsupported case to bulge? If the pressure is high enough that is a certainty. If you have gas pressures over, my guess, about 3000 PSI with an unsupported case it will not only bulge I think it will burst like a balloon.

Second question is can you develop enough pressure in a reloading press if the case is unvented? Boyles Law and my classes in basic Physics provides an absolute answer of NO to that question.

Here's why. Boyle's Law states that the rise in gas pressure in relation to a change in its volume is a directly linear relationship. Meaning if you reduce the gas volume by a factor of Two you will increase the pressure by a factor of Two. So, when your case first engages the sizing die and forms a seal there will be a minimum of 2 times the case volume that is "trapped" in the die. Bring that case fully into the die and you have a maximum reduction in volume of 1 case volume. So the pressure within that enclosed volume will be a maximum of 1 atmosphere. Since 1 atmosphere is equal to 14.7 psi at Sea Level your increase in pressure will be 14.7 psi, provided you are at Sea Level. Because there is most likely a rather considerable gap of airspace above you case when it's fully engaged in the die I would expect that your actual developed pressure will be in the range of 5 to 9 psi.

I expect that those bulges you noted were caused by an unsupported chamber during firing and your setup doesn't typically size the case for it's full length. I also expect that these cases were ones you found on the floor of the range you were shooting at that you picked up assuming they were your cases. Shoot at public ranges and no matter how careful you are about trying to recover just your cases sooner or later you'll get a stray from a neighboring shooter. If that shooter was using an older Glock, or a similar unsupported chamber firearm, you will end up with "Glocked" brass sooner or later. Good news is that the Lee Factory Crimp Dies can be turned in to a Bulge Buster simply be removing the top plug ans sizing ring and using something as simple as a nail to push a case completely thru the die. Lee even sells a Bulge Buster Kit specifically to do this.

The other thing you can try is running the loaded round through a taper crimp die.

cmj8591 said:

The other thing you can try is running the loaded round through a taper crimp die.

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And likely overcrimp and deform the bullet at the same time.

Hmmm, you do know that the factories all use taper crime dies?