I'm a believer in the Redding Body Die. I use them for the 223, 308 and 30-06.
They can be used at the time of reloading or when you find a round won't chamber without excessive force. I have safely used the loaded round in my press with the Body Die, resulting in a perfectly resized case that chambered smoothly.
The body die will resize the case and bump the shoulder back, so you really need to use a lube to be on the safe side. I prefer using Imperial Wax/Lube.
I set the body die up in this fashion:
1. Remove the firing pin from the bolt. I use the Rem 700, so it's very easy - other makes, leave the firing pin in, if you want but know the feel for closing the bolt on a commercial round and strive for the same pressure.
2. Run a lubed case through the body die, wipe off lube and attempt to chamber the round. The bolt should close using finger pressure. If the bolt doesn't close or takes effort to chamber - turn the die down 1/4 turn and repeat until you get the bolt to close with finger pressure.
If the bolt closes by itself - just drops down on the chamber case - that means you've bumped the shoulder way to much - turn the die back up 1/4 turn until you get the desired pressure. That case will have excessive headspace, so don't load max plus with that particular case. Keep using different unsized cases to find the sweet spot, if the bolt initially closed by itself.
Once you have it set - you're golden for that particular firearm and by running your case through the body die - it will chamber that round like a hot knife going through soft butter.
Different firearm - start over and do it right again.
That's how I do it and it's always worked for me 100% of the time and I've been at it for awhile.
I've currently got one on order from Hornady for a wildcat 22 centerfire. It cost a $bunch compared to the commercial Redding Body Die but I feel I need it. Ben is the technician at Hornady and his turn around time back last June was 12-15 weeks, so I'm getting close.