Wanted a pair of blow up barrels to take to a show . So we took an old 2&1,2" gun stuffed some paper in the barrels ,loaded it with a 2&3/4" cartridge , stuck the ends into the ground next to a fence post which we taped the gun to .
Pulled the trigger with a long string and the gunshot near 4 feet into the air .
Took us three attempts .
By contrasts a 20 bore that had just passed re-proof was returned to us a week or so later with the end blow off in normal use .