I have made a reactive target using a frying pan, two bits of steel and some Hilti nail gun cartridges.
The frying pan doubles up as main frame & back stop and also amplifies the sound.

I got the idea from the `rondo` which is a cleverly designed devices using 6mm blank cartridges.
its commercially available and well made, but I like to make stuff myself.

the holes for the blanks are 7mm dia, which is tight enough to hold the blanks in the back sheet but large enough to be able to hit them with a .177 pellet