Kentucky Gun Company runs the full details of the Air-Ordnance SMG .22 pellet gun, which looks like it is a pain to load but a lot of squee to unload.
Built on a paintball-style platform with a .45 pistol grip, it is powered by CO2, nitrogen, or HPA (high pressure compressed air) and is fed with a 100-round belt. Velocity is billed at 600fps by Air-Ord, which lists the adjustable rate of fire at up to 720 pellets per minute, or about 12 plinks per second. On full-auto it sounds like a sewing machine.
Eric from KGC found it ran a bit slower velocity wise (due to a funky bottle) and kinda loud in their range test, but fairly accurate using a Sun-Optics red dot in both plink and plink-plink-plink settings.
These things look really sweet. Of course, they are $500-$600, so there’s that.