a "re-learning" process

I've been fine tuning my sub-sonic 147 grain 9mm loading and encountered a problem I knew about but hadn't given any thought. Those bullets have a sharp full diameter heel which I discovered to my dismay caused a significant case bulge on some brands of brass. I guess I'd just lucked out with the initial loads using a handful of cases from a coffee can of mixed brass.
I only had to pull 20 or so bullets because the loads wouldn't chamber. I had to dig through the brass stash for a can of Federal brass as that brand is the only stuff that doesn't swell too much when 147 grain bullets are seated to fit MagPul magazines. On the plus side, I did stumble onto several hundred 147 grain cast lead bullets I forgot I had. At 950-1000 fps, those may provide cheap practice loads once the bore gets smoothed up a bit.

For such a simple seeming caliber & round,, the 9mm can be a PIA to reload properly & safely.
I like to attribute it to the wide variations across the world we encounter with this caliber.
Nobody has standards of case dimensions, which, when it comes to reloading,, is critical. Throw in the seating depth, which can quickly affect pressures, the 9mm can be a "problem child."
Yet,, it is often loaded by many,, and used quite easily in many guns.

Would a Lee factory crimp die iron that bulge out so they could chamber?

Why use 147 grain? Do they shoot better than 115 or 124 which are certainly more common. Just curious, I only recently tried 124 grain 9mm and usually just stick to 115 for a plinking round.

"Why use 147 grain? Do they shoot better than 115 or 124"

Simple answer is these loads are specifically tailored for my suppressed PDW project. None of the factory ammo I tried stayed sub-sonic from the 10.5" barrel so I'm reloading the heavy 147 grainers to the required level. It's easier to hit that velocity at a pressure that functions properly using the 147's. I chose the bullets that provide best terminal performance and unfortunately, they also created some headaches due to bullet length and the square base profile.
My 9mm handgun carry ammo is 124 which produces the best compromise of expansion and penetration. I'd be using the same in the PDW project if it wasn't for the sub-sonic requirement.

I understand your dilemma. But some things just are; a longer bullet seated deeply in a case with a tapered ID and some thing's gotta give. In your case the case expands beyond an acceptable diameter, so chambering is problematic. I would try sorting brass for cases that work with long/fat bullets and perhaps seating them as long as possible. If you tried a Lee FCD it would more than likely swage your cast bullets and leading and inaccuracy will prolly result...

Federal brass is working well enough. Still a little ripple but not causing chambering problems. I can see the bottom of the can that held the first 500 bullets and have enough Federal brass left to load the remainder of the 1000 bullets.

Mobuck, you might try the Hornady 147 XTP as it is a boattail bullet and may not affect your brass as much. Come to think of it, that might be why it is a boattail bullet. The are extremely accurate and, of course, Hornady, and others, load them in factory ammo without bulged cases, All brass gets thicker the closer one gets to the to the rim(bottom) of the case and the 9mm was designed around 123/124 grain bullets. An extra long bullet in any straight wall case would do the same. Bob! 8)

Thanks rangerbob. I've been looking at some of the Hornady blems @ Midway. I already scored 1000 of the high performance Federal HST bullets and have enough Federal cases to use for those. Another 500 of the Hornady bullets would give me a long term supply of sub-sonic ammo for this platform since I only need this bullet weight when/if desiring the most quiet shooting. I can buy practice ammo at less cost than loading my own hollow point sub-sonic.

LEE factory crimp die ordered. We'll see if this solves the problem(s).
I received another 9mm barrel(this one a Rosco brand) and the chamber is even tighter than the first 9mm barrel. Apparently the handguns I've been shooting similar ammo in have much looser chambers.
Received the LEE die today and ran a bunch of the "rejects" through this evening. All dropped in fully and fell out of the chamber when the muzzle was elevated. Looks like I'll have an added step in the loading process just to make sure I don't have a jam at a bad time.

Awesome, I've had good success with the FCD. I loaded some 147 poly coats from Badman bullets & used the crimp die. Out of curiosity I pulled a bullet & measured it- still .356. The FCD can swage bullets but doesn't have to if you don't overdo it-Dave