mark ii disassembly problem

i recently bought a used mark ii standard s/s (1985 build) to remove the barrel/receiver from the frame requires major force. i have have had many mark series over the years but none required this type of force.(all my others require just a couple of taps) i have to use a 2lb plastic hammer to seperate the parts.

any thoughts as to why this one is so difficult

i have had a few like that they were accurate.i never tried to loosen them up just pounded them back on.

When you go to assemble it put some lube on the frame where it engages the barrel assembly.
Tight is good....

Quite often we have found that the FIRST one of them has to come apart, it can be a "bear"...usually you can tell if there is any buildup along the top edge of the grip frame, so a drop or two of Kroil or some such, does help..we never use a hammer or mallet, to "pound" off or even back on,just a piece of carpet remnant on the bench top to smack the frame down on and pop it off, works EVERY time..........
usually the stainless models are the worst,seems the metal galls, careful you do not slice your hand on some of the frames edges, they can be sharp!!!

thanks for the tip