QB 78 cocking and hammer pin question

[jpsgunworks]

   I recently got a QB 78 that was taken apart and in a box by it's former owner .  It's missing the cocking and hammer pins
and the safety . I can make round pin but the square head one would be a pain  .  I assume the square shape has something to
do with contact bearing  area but was wondering if anyone has run these on two round pins and if it will hurt .  Any suggestions
on  making  a safety ?  Thanks

[nervoustrigger]

I’ve worked on others’ QBs that had a plain round pin in the spring guide.  However I normally remove it altogether, and drill and tap the end cap for a #10-32 screw to act as a RVA.  That lets you dial in the hammer spring tension just right rather than the trial and error affair that is usually required.  This change also converts it to cock-on-open rather than cock-on-close, which I find to be both more natural and makes it so you can feel any potential problems with seating a pellet.
 
Anyway if you stick with it, the pin’s projection should be 0.250”.  A tolerance of ten thousandths +/- won’t matter.  Better to go shorter than longer.

[Ribbonstone]

You can run them with two round pins.  Square head might be better, but haven't had any problems when I had to do without.