It seems that they are practically "unobtanium" and way back when Beeman sold parts the solution was to buy a "pivot bolt and nut as a set" at a cost of $10 (decades ago).
Well, the factory HW pivot bolt lock nut has a weird M7x.75 fine thread with very few threads engaged for tightening. This is indeed a recipe for damage due to "ham fisted torquing" of which I've been guilty on more than one occasion!
Since M7x.75 bolts are indeed practically non-existant in the USA as are the taps and dies my solution to making my own came when I visited a Harbor Freight store. I noticed that one of the cheap tap and die sets (about $17 included both a M7x.75 tap and die.............
These taps/dies are only carbon steel, however I figured that the 7mm would be fine for occasional work and I was right. Here is a stripped HW pivot bolt lock nut showing the ravages of filing away the "slot burrs"............
Now here is the home machined and blackened replacement........
No lock washer needed so there are a few more threads engaged when tightened and the pivot bolt is indeed LOCKED in place!
I also found that the HW95 trigger guard screw large had a M7x.75 thread so I made one of those to replace the slotted factory version...........