Originally Posted by Vikingdad
Also unsafe and illegal. Bad advice.
Actually, vikingdad, there is a couple legal inserts for the 26.5mm milsurp flare guns. They come in .22lr and .410/.45lc. I have the .22lr adapter, fun to shoot. It comes with a BATF certification letter, stating combing the adapter with the flare gun makes it a Title 1 firearm. It's perfectly legal. It's definitely not accurate, but it's good for the BOB or somethin.
If you have a 37mm with a 26.5mm adapter, or a CZ BRNO flare rifle, you can get a 12 gauge shotshell adapter, but it must be use in a registered DD (your launcher must be a registered destructive device).