when I worked with my 788 (late seventies) I recut the threads and bored the receiver ring deeper so I could use a close fitting counterbore to control lateral deflection of the bolt head. I also installed agjustment screws and separated the sear spring from the trigger lever. I was able to set this trigger at ten ounces. I barreled this in 219 Wasp using 225 Winchester brass and it was a decent light varminter for the time. Later, I re-barrelled to 6PPC and it was even better. Always had a slight tendency to shoot vertical groups ( still 1/4 moa but vertical nonetheless) and shot better at 200 than at 100. Loaded hot, cases would stretch a bit.
Anyway, lateral stringing is often a scope problem but may also be an indicator of a bedding problem. WH
I found a PDF file of the original Article by Paul Dorsey explaining the trigger modification with a drawing of the screw hole locations. That is going to be my weekend project.. Thanks for the Info!!