Okay so here is my issue.  I have several threaded barrels for my glocks (all 9mm) and have run into an issue.

My Glock 19 which has an AAC threaded Barrel made by storm lake seems to have a super tight chamber.  My reloads have about a 10% fail rate in this gun.  I don't really want to switch barrels because it is very accurate, but I do want my loads to chamber across the board.

Here is my setup
Lee Pro 1000 with 3 stages
Full length carbide resize die
Powder though expanding die
Bullet seat/ crimp die
Range brass

1st: would switching to the lee undersized resize die help.  They say it makes case .003 smaller than the factory die.

2nd: if I get that die I would like to resize the loads that don't pass plunk test can you remove the decapping pin and resize a loaded round?

Thanks all.

Pictures just cause.    

I think you should try a Lee factory crimp die first.  It solved a lot of problems for me.  I would not try to seat and crimp at the same time.

Are you shooting lead, plated, coated or FMJ?  I've also found that a larger bell helps a lot on the lead and coated bullets I use.  Keeps stuff from gumming up the case mouth that will keep the round from chambering.

I know you're doing a plunk test, but a case gauge may help you work things out.  It should be tighter than your chamber so if it plunks there, you won't have an issue in competition.  Anything of mine that doesn't pass the gauge gets tested in the barrel.  If it's OK there, I use it for training ammo or at matches where I can't pick up brass.

**edit
Forgot the last question.  No, you can't resize a loaded round.  It'll swage the bullet down even if there's enough room at the top of the die for the bullet sticking out.  The Lee factory die sorta does that at the bottom of the case.

The biggest problem I have now is buggered up rims that keep rounds from passing the gauge.  They chamber and extract just fine in the barrel, but I don't use them for when it counts, just practice and muddy days.

Let's diagnose the failure before we start trying to fix it.

When you say the rounds "fail", what do you mean?  Do you mean they fail to chamber?  Fail to fire?  Fail to extract?   If your problem is that the slide will not close fully on them then take a couple of filing rounds, color them with a Sharpie and try chambering them again.  When you eject them, note where the Sharpie has been worn off the case.  The is the first place to look for a solution.

I'm going to assume the result and continue.  If the problem is at the case mouth then you probably just aren't removing the belling of the case mouth adequately when you seat the bullet.  Adjust the seater die down a little bit at the same time you're adjusting the seater stem up (so that you don't seat the bullet any deeper).  This will increase the crimp applied by the seater die.  Retry the Sharpie test and adjust the crimp as needed to fully remove the belling at the case mouth.  If this is the problem, you will eventually find the sweet spot.

I started loading 9mmm with a Lee die set.  The powder through expander and I did not get along.  Either I couldn't get enough expansion and the bullet would collapse the occasional case mouth or the mouth looked like a Pilgrim's blunderbus.  I have Lee dies.  I use Lee dies.  But I retired my set of 9mm Lee dies and got an RCBS 9mm die set and all of my problems went away overnight.

If the Sharpie shows the case is binding near the case head, then the brass may be a little large.  The conventional resizer die cannot get at the part of the case that is surrounded by the shell holder and so a little bit near the head escapes being resized.  The Lee FCD die is designed to solve this problem.  

I don't use a Lee FCD because I am opposed to the very idea of performing a "post-sizing" operation on a cartridge and so I use a micrometer on each case as it enters my reloading stream and if the diameter near the case head is too big, it is simply recycled.  By intercepting outsized brass before it enters the reloading stream, I save myself the time and trouble of running everything through year another die, but if what I do seems like a lot of work to you, then by all means make the investment in the FCD.  You won't be disappointed.

If the Sharpie mark was somewhere else, PM me and I'll be happy to work with you to diagnose the problem.

The previous post is absolutely correct. Most chambering issues with semiautomatic pistol has to do with leade not cartridge diameter.

I'd bet your bullets are hitting the rifling on the Glock.

I very simple way to tell is make a dummy round then seat the bullet a little deeper in .010" increments plunk testing between each adjustment.

If you do find it passes plunk test you have 2 options.

1) Do a load work up at this OAL and use it in all of your pistols.

2) Have the leade cut on the Glock. This is actually a very common thing. Maybe not particularly with Glocks but with semiautomatic pistols in general.

BTW: There is absolutely nothing wrong with seating and crimping semiautomatic pistol ammo. You are only removing the mouth flare. The case mouth should never become small enough to effect the bullet.

It doesn't create a functional crimp either. It simply removes the mouth flare nothing more.

Motor

Shooting plated mostly.  

Montana Gold 124 JHP
XTREME 147 RN Plated

I have a crimp die in my set but would I need to put that in a separate press?

Also it is definitely the bottom bulge that is he issue.  I have plunked just resized cases now and some don't drop in.

My 147 are 1.15 OAL
My 124 are 1.10 OAL

I will try to reset seating die to crimp more.

I will try and take some picture of rounds in chambers.

If you'll look in your reloading manual at the cartridge drawing, it'll show the case mouth is supposed to be .380" max.  I set my crimp to give me .378" to .377"  I just measure with calipers with the flat part of the blade 1/2 on and 1/2 above the case mouth.

If you over crimp a plated bullet, you can damage the plating and hurt accuracy.

If you really over crimp any bullet, you can bulge the bottom of the case as it gets pressed down.  That's a common issue with bottle neck cases at the shoulder if they're over crimped.


****edit
As noted above, if the bullet is out too far and is engaging the rifling, you'll have issues chambering - and high pressure.  Are your bullets seated deep enough to pass the plunk test?

If sized empty casings won't fit that's definitely a problem.

Make sure you are sizing as far down as possible but you don't want your carbide die to come into contact with the shell holder.

If the bulge is actually the problem and not the OAL the smaller sizing die may fix it. A Lee FCD would probably fix it too but that of course would mean an extra step in your process.

I'm not against seating and crimping in 2 steps. When I load on the progressive press I seat and crimp in 2 steps. Crimping is the most misunderstood process in reloading and there's no way for the user to see what's happening while it's happening so to many it seems like voodoo magic.

Motor

Okay these are all picks of the same loaded round.  What do y'all think.  

Today I did a reset of the press after those pictures.  I think the resizing die may have been too snug and when the bullet was being seated it was creating a bulge at bullet base.  


It seems to have fixed the issue.  I loaded 25 rounds testing each one and they were all good.

Will update when I get at least 50 more loaded.

I don't know if it's an optional illusion or not but zooming in on your photo it does look like excessive crimp.

I hope you got it sorted out now but here is a little "how to" for setting up to seat and remove mouth flare in one step.

1) Back the die off so it won't reduce the mouth flare and seat a bullet to your desired OAL.

2) Back off the seating stem so it can't contact the seated bullet. Then with the ram at the top of it's travel screw the die down until you feel it contacting the mouth flare.

Then adjust it down a little at a time. Each time you move it measure the cartridge behind the case mouth where the bullet is inside the casing and while holding gentle pressure on your calipers slide them forward to the case mouth.

You want this dimension to be the same. When it's the same you have removed the mouth flare.

3) Lock the lock ring saving your crimp setting. Run the cartridge back into the die and screw the seating stem down until it makes solid contact with the bullet. Snug the seating stem lock nut.

You may need to tweek the AOL a little but your crimp should be good to go basically for ever unless you use casings that are a fair amount longer or shorter.  

If you decide to use a different bullet it's no big deal. Just back the die off so it won't reduce the mouth flare, seat your new bullet to the OAL you want, back off the seating stem, screw the die back down against the lock ring, run the cartridge back into the die, then screw the seating stem down to the bullet.

You should never have to re-set the "crimp" unless as I already stated you get casings that are a fair amount longer or shorter than what you have now.

Motor