Bren Gun Question

[albayo]

A friend of mine came across a Bren mag that was manufactured for blanks only.

There is a steel spacer in the front of the mag that will only accommodate blanks. Dos this have to be blocked to 5 round even though 303 ball will not fit in it?

Has anyone ever seen one of these?
What value would one put on this kind of mag?

 

[RobSmith]

I'd say yes, blanks, it is still a magazine and can still fit a firearm.