Dennis, your situation is not that uncommon.....
I buy a lot of once fired brass from guys that are testing rifles at the factory.
I usually take .003 off the top of the shell holder which will allow the case to go further up in the die, reducing the dia. at the web.
Your Co Ax press is not the best for this type of situation. The Rock Chuker and similar types will get more leverage on these really tough sizing operations.
I have found that in my minimum spec match chambers, that shooting brass from other rifles, especially factory rifles, leads to your problem almost every time. The brass when fired in the larger chamber, wants to retain that memory...I am sure that I am preaching to the choir in this instance.
Bottom line, the factory brass in unfired condition is probably .002 under the match reamer specifications. Fire that over sized brass in an over sized factory chamber, then try to full length size the brass to a Match chamber, you are screwed almost every time. Taking .003 off the shell holder, which pushes back the shoulder further, and sizes more of the base, may help, and it also may shorten case life if you push back the shoulder more than .006, which is the price you pay.
Good luck