We are looking at the 9mm full auto grease gun used by WW11re-enactment groups, to add a bit more noise to fire fights.
The TL SFX MK1 FRAG.GRENADE IS the groups standard pyro used with good effect then contact is made with hostile forces, a loudish bang with a harmless puff of smoke. Mainly carried in our rucks, around 12 per man.