The "Used brass hard to extract" thread is a timely one for me. I ran into a similar problem with my latest 6BR barrel. When I reload fire-formed cases the first time, I just neck size them. That has always worked fine, but this time when I went to seat the bullet with my Wilson seater, the case got stuck in the die. A little investigation revealed the head measured .4720 - .4725. I measured the heads on cases fired in my Savage LRPV and got .4705 - .4710. Those work in the Wilson seater just fine after being neck sized. I checked my reamer that was used on the custom barrel and found that it measured .4735. I returned it to the mfg. and he re-worked it so that it measured .4720 like it should have in the first place. As it turns out, there was a problem with the barrel too, so that is being replaced by the mfg as well. I will get back a new barrel that the fire-formed cases will not fit because of the new, tighter chamber.
Now, what I hear you all saying is that I cannot full length size these cases to fit into the new, tighter chamber. Is that correct? I have already fl sized all of them (with a Forster fls) and they fit fine in the Wilson seater now and they measure .4715. They fit in the Savage, but they are a bit tight (I'm wondering if it might be the shoulder being too far forward and not the head size). They may be a bit tight in the new custom chamber as well. I will find out when I get the new barrel back.
Now, what I hear you all saying is that I cannot full length size these cases to fit into the new, tighter chamber. Is that correct? I have already fl sized all of them (with a Forster fls) and they fit fine in the Wilson seater now and they measure .4715. They fit in the Savage, but they are a bit tight (I'm wondering if it might be the shoulder being too far forward and not the head size). They may be a bit tight in the new custom chamber as well. I will find out when I get the new barrel back.