Looks like I waited just a little too long to revisit this and my original thread disappeared, so please bear with me.
The gist of my problem is that when reloading .223 rounds for my 5.56x45, 1/9, 16" HBAR Bushmaster carbine, some cartridges seem to get stuck in the chamber before firing. I discovered this by accident when for some reason I stopped shooting a string before the mag was empty, and the bolt was stuck TIGHT when I tried to work the charging handle to eject the unfired case.
I posted this a week or two ago and got several thoughtful suggestions. The main suspect as I recall was possibly that I could be somehow partially collapsing the case shoulder during resizing or seating/crimping, which could make the outer diameter of the case be a little larger than it should be. A second possibility was that maybe I wasn't going all the way down to the cartridge base when resizing, and that maybe the base of the cartridge was oversize as a result.
I will hopefully get a chance today to test the second idea out, as I made another batch of rounds and made darned sure to go ALL THE WAY DOWN when resizing these. I have another batch of reloads I'd made where I didn't pay special attention to this detail, so I'm going to try both and see if I can duplicate the problem. (Both lots of reloads are using the same "R-P 223" brass)
My question today is, if the first problem, an oversized shoulder, is the case, what would you do to try to fix it? I use all Lee dies, and as I do with all my rifle reloads, I use 3 Lee dies (sizing/decapping, seating, and factory crimp die). I don't think my bullet seating operation is the culprit, as all it does is to seat the bullet. I like to put a decent crimp on my cases with the FCD, is there any possibility that the FCD is putting too much downward force on the case shoulder?
I measured the shoulders of some of my cases with calipers and compared them to some Remington 223 store-bought ammo I have. The shoulders on the commercial ammo seem to me to be about 0.350" whereas mine are about 0.352". It's hard to tell for sure because the measurement is made on the part of the case where it starts to taper off. The other thing that's kind of odd is, what IS the shoulder size supposed to be? I found the diagram below online, but it's a little different from the one in my Lee #2 guide. Lee says the shoulder should be 0.350" but this one below says 0.354".
Anyway, forgive the rambling, long story short is that I suspect that I may have a shoulder issue on my 223 reloads, perhaps somehow related to partially collapsing the shoulder at some point. Any suggestions on what I should do differently? I reload 3 other rifle calibers, do things the exact same way I do with these, and have never had this kind of problem. I'm curious as to what the peanut gallery might have to offer for advice.