The rest makes 0 sense
Your most accurate load for a given rifle is still going to be in a given pressure range .
By reducing the 3F load , what your doing is dropping the pressure closer to what 2F would provide .
I didn't say that it made sense.....just reporting the rationale as I have heard it. As I understand it, the pressure profile is a different curve than, let's say FFg. Narrower, I suppose. The peak is arrived at more quickly. I am guessing that it would be easier to get into an overpressure excursion. Assuming the same weight powder charge, let's say 90 grains, that 90 of FFFg is going to produce more pressure (or is it the same pressure more quickly?) than an equivalent load of FFg assuming that the same weight projectile is used.
The duplexing of BP with smokeless is what I was referring to in the Lyman book and in the Matthews books.
A typical entry in Lyman - 50/90 Sharps: 498 grain cast bullet, 7.1 grains of SR4759 and 63 grains of FFg (Max load). The rule of thumb is 10% of the total weight of the charge is smokeless.
Pete
