Hello, New Forum Member Here...
Just thought I would 'Chime-in', as I also have a P6(1979 vintage), and absolutely Love-it !!!
Here's what I have done to Mine;
Replaced Stock Grips w/Pachmayr's...
Replaced Hammer-Spring w/19lb. from Topgun Supply...
Polished Feed-ramp(myself), and some of the Internals
...
The P6 has Never had any Issues whatsoever w/JHP, or anything I've Fed-it...