Made replacement PB pivot washers for my two XM's. Action is smooth as original teflon that came with.
Noticed impurity impregnated into original soft teflon washers as well and blade tange pivot area revealed tale tale circumferential scratch lines mirror'ed those on the washers. Slicer is two years old and Wharnie is new, so no excessive deployment were involved nor exposures to gritty/unclean environments.
With original teflon washers, due to support of the two stop pins prevent blade side to side movements in the open position, but when closed and push, an inch from the tip, there will have significant deflection on the lock bar side and less so on the presentation side. Having PB in place, previous side to side is no longer there.
Here is the size, if anyone is interested for the improvement:
XM-18 3.5" pivot washer, original OD - large is 1/2", lock bar small side is 7/16", ID is 1/4" and 1/64" thk. It is basically from die punched teflon 1/64" stock.
I made mine a little different to maximize support/fit: OD Large/small - .520"/.460". ID - .251" and mirror's final finished at .015" thk.