My loads are producing some very small groups in past experiments crimping has enlarged my groups.
Exactly, but that may not be due to bullet deformation. Crimping increases pressure at ignition, forcing the powder to burn just a bit differently.
I also find better accuracy with no crimp, but a loader can crimp from just a touch, to a full roll crimp. If your stuck believing that all dies must be set against the shell holder, and all moves must be a "cam over" of the press your limiting what you can do when you load,
Anyways, this is important,,
CW this is my first set of Lee dies I have always used RCBS on every thing but my old 308 dies were getting a little aged so I sold them in a garage sale and bought the Lees. What I don't like on the Lee set is the O-rings, aluminum parts and there is no way to lock the setting down solid.
That's interesting because I bought Lee dies for my 308 just to try'm, all my others are RCBS, I've struggled with the Lees too, and just got some RCBS in 308 and now I'm happy.
If your trouble just started with the Lees then it's the change in the button and or the entire neck sizing of the die thats causing the trouble. As stated by others, try turning the button down a bit and hopefully you get what you need.
Now that I've been able to "prove" my RCBS dies I'll be putting the Lees up for sale or trade.