Originally Posted by
Outpost75
The "full charge" used for assembling 158 LRN service loads was 3.5-3.6 grains of Bullseye.
The "mid range" charge normally used for 148-grain HB wadcutters was 2.7-2.8 grains of Bullseye.
Powder charge was determined by test firings. Powder charge was adjusted by selection of the correct thickness powder plate. These were marked and graduated in 1mm increments and several could be stacked together to create any volume needed.
The 3.5 grain "full charge" wadcutter produced 855 +/- 25 fps from a 6-inch "solid" test barrel, vs. 770 fps for the "mid range" wadcutter.
I would agree that the previous poster that a 4.5 grain charge with a solid-based BBWC bullet is VERY probably +P.