That caution about using FFFg in rifles is fairly common. I don't know the original source but have heard it before. I have heard it as "Don't use in rifles" as "Don't use in calibers larger than .50".
The theory is that the finer granulation, as compared to Fg or FFg, exposes more surface area to the flame front and thus the powder burns more quickly and pressure spikes more sharply. Seems that FFFg use in smoothbores is not subject to the same caution...at least I have not read about that. The most I have read (and done) is to reduce charges by 10% from FFg.
But what would happen if you mistakenly loaded a max charge of smokeless in place of BP or its equivalent. So while we maybe able to say ; who would ever do that .
I am trying to envision a scenario in which such a thing could happen "mistakenly". I cannot imagine circumstances under which such a mistake could be made. I can imagine someone doing such a thing out of ignorance of the consequences but that is not the same thing as mistakenly loading as described.
If I were at the range or hunting, I would have to be carrying a flask of smokeless propellant along with my BP. I'd have to have filled that flask at home.
Duplexing....the Lyman Cast Bullet manual has quite a few loads that are duplexed. Paul Matthews in his books about BPCRs frequently mentions duplex loads.
If I want to use a sub powder like Pyrodex or 777 in my flint guns, I have to duplex with BP to kick start.
Pete
