Mortar powder charge and grade question....

[Soot Sucker]

Hello all,

     I recently ordered a bronze "British grenade mortar" from Cannon LTD. it has a 2 1/2" bore and has an aprox       7 1/2" barrel length. I do not have the powder chamber dimensions. I will be firing iron shot weighing 2 lbs. My question(s) are
Given the weight of the shot/projectile that will be fired, should I use a slower burning powder i.e. FG ? OR...  because of the mortar's short length should I use a faster burning powder i.e. FFFG such as I now use in my golf ball mortar???
I need to know kinda quick as I am about to order a 25lb lot of black powder from a nearby Goex distributor, and would be picking it up Sat.  I can mix and match powder grade so I need to know what grade or grades I can  use.
Also, what volume charge should I start with?

Thanks,
Dave
PS. BTW...If I order 25 lbs the price is $7.80 per pound (picked up) from the distributor... not bad huh?  :wink:

[Double D]

Stick with Fg or get Cannon Grade.  I buy my powder from Back Creek Gunshop outside of Winchester VA adjacent to the Ft. Shenandoah N-SSA ground.  I bought 1 lb for about that price.

When you find out what diameter the powder chamber is I'll look up your max charge for you.