To be honest, we purchased the insert but have never tested it. It would be a last minute decision with no other option. I have a military flare gun for 25mm shells, really well built of steel as the one I'd use for it but the Orion metal gun (blue & white) is a pretty good flare gun. The insert is aluminum.

Interesting reading the below link from the Dept of Justice. The FBI did tests and came to the conclusion.

"With the adapters completed, FTB personnel conducted live fire testing. The live fire testing resulted in the eventual destruction of all four flare launchers, and confirmed that the use of these adapters in conjunction with conventional ammunition is likely to result in a catastrophic failure of the flare launcher."

I wonder what "eventual destruction" means???? Did they shoot it once or 100 times before it failed? As I said above,, for me it would be a decision with no other option available. I'd be more likely to use the pepper spray shells. Tried them on a wall. It would be a good deterrent.

Here's a link from the 'Department of Justice' http://www.atf.gov/press/releases/2006/05/050406-openletter-nfa-flare-inserts.html