Paper Shot?

[altec]

I was searching the IWM Photo Archive for pictures of the 5.25 AA Gun when I came across the attached. The not on the rear makes reference to the use of a Paper Shot which sound like it's being used to proof the mounting and presumably break up afte firing? Any information on this would be appreciated.

 

[tankbarrell]

Most guns had a paper shot and it was for how you surmise. The shot was a long cardboard tube, usually filled with sand and broke apart due to centrifugal forces upon exiting the muzzle. They had enough mass to operate the recoil and semi automatic systems. The 17 pdr paper shot was 23" long to give you some idea.

 

[sgdbdr]

Something like that :

 

[altec]

Thank-you both, that answers it perfectly.