I have found...
...A chart which shows what appears to be a good comparison between pressure over time from BP versus pressure over time for smokeless.
I see four things:
1. BP begins to develop pressure more quickly than smokeless.
2. Smokeless rises to its maximum at almost exactly the same time as BP rises to its max.
3. Smokeless develops twice as much maximum pressure.
4. BP pressure declines more slowly than smokeless.
I do not know how the volumes or weights of powder were decided upon for this chart. I don't know the length of the barrel (except for the fact that the bullet exited the barrel after 1.1 millisecond in both tests, which may inform us as to how the charge was decided upon.) I don't know the characteristics of the projectile.
I also saw a chart which implied that a 45-70 with BP develops 25000 PSI.
My reading of history convinces me that most bad government results from too much government. Thomas Jefferson