Marker Q's [TANKS]

[Christopher Clark <cjkkclark-at-comcast.net>]

Hey everyone,
Two quick marker questions: first, I wanted to know what velocity the 
paintballs are fired at?  I think I remember reading 150fps, but I 
wasn't sure.  If this is the case, how do you all calibrate at the 
battle sites?
My second question is for Chris B. on the design of his homemade 
"canon".  I understand if you don't want to reveal any trade secrets, 
but would you be kind enough to discuss your newer design (the one in 
the Stug and Elefant)?  Do you have any new pictures to add?  One of my 
dream projects, which I think a few others have also mentioned, is to 
build a Katyusha, and the homemade design is the way to go for 
expense's sake.  I was thinking of designing a multi-chamber system 
that draws from a single CO2 cyclinder with some sort of 
electromagnetic action to fire the balls simultaneously.
Thanks,
Chris "the wife probably won't go for it but it'd be fun to have" Clark