I just picked this up as an alternative to The Sword and The Flame Darkest Africa and read through it. Its a fairly decent system for its size and what it hopes to accomplish. I liked it enough I also bought Blast Pistol and Last Era.
I was looking for something generic for the group I game with, they don't have the patience for detailed rule sets. The fact you used the same attributes for all three games is what drew me in.
Powder and Bayonet is good the way it is! Blast Pistol and Last Era need the following…
#1 More skills /traits/ abilities
#2 More troops types (ahem space marines wearing heavy armor)
#3 Expanded weapon lists for Blast Pistol and Last Era
#4 A spell list for Last Era (i.e 20 spells should do it)
#5 Compile your various expansions in an organized way so I won't be looking for different skill, equipment and vehicles through multiple expansions.
I have seen your expansions and will probably order them in the near future. I am just giving you and idea of what I would like to see.