Now as to the controllability of the 51 my personal opinion is if you can't control this weapon with standard ammo in it's pistol configuration then maybe you need to find another line of work
I get so annoyed with mall ninjas crying about how this weapon is a "toy" just because they can't handle a weapon with a little fire and kick…
Sorry, but it is a toy. A fun toy too. You want even more fun? Get a 51K. I've got a G-3, 2 51's and a 51K, wouldn't trade them for the world... well maybe.
As for kick, the 51's and the 51K has a lot LESS kick than the G-3. Now I'm talking about full auto in all cases here. The G-3 is like hanging on to an insane Pogo Stick in full auto. The 51K isn't unpleasant at all.
Depending on which ammo you're using at the time will determine just how much fire you'll get. Most military rounds have flash suppressant in the powder mix, most commercial ammo doesn't. SOME military ammo also does have the flash suppressant but finding it (assuming you WANT flash) is getting harder and harder as available stocks of ammo continue to dwindle. Most notably, the early corrosive Chinese copper washed 308 was VERY bright ammo, so was the Turkish 8mm Mauser ammo.
All depends on what floats yer boat.