This is a newbie question, so excuse me for my ignorance if this info is already posted.
 
 I would like to build a Tennis ball Mortar. 
 Does anyone have plans for this type of thing? I have seen plans for golf ball mortars, but not for tennis balls. I think golf balls may be denser of a projectile than I want to shoot. I think with a tennis ball, I lab would retrieve the ball. ;-)  
 
 Using FFF black powder, What is the appropriate load for this design?
     Sub Question: How do I calculate a “maximum” load that will not hurt me?
 
 What metal should I mill this out of?  
 [font=]Can I get by with 1045 or 1020?[/size][/font]
[font=]Thanks,
Mennelabs[/font]