I own several Federal Riot Guns, two Tru Flite 37mm Super Long Range Gas Guns, and a british Webley-Schermuly Multi-Purpose Gun like the v-10 blaster on star wars. I reload and usually shoot them about 500 times a month.
You can use just the #209 shotgun primer and it will launch most projects a good distance. Maybe 75 yards with the right primer. The hottest 209 primers are under $0.03 per primer usually, which means that the 37mm is cheaper to shoot than a .22lr if you can recover the nose cone of the flare.
Buy the aluminum hulls, that hull adds extra strength against a kaboom. Don’t want to be like this guy.
https://boston.cbslocal.com/2018/04/...cher-explodes/
Did I mention how easy it is to reload. Pop the old primer out, put the nose cone in by hand, put the new primer in. I have reloaded the same casing 5 times in 54 seconds.