I think youll have that issue with a lot of things people have cobbled together of late.
Once youre shown the proper technique, its actually very simple to shoot most shoulder fired pistol and intermediate rifle rounds, and actually do complete mag dumps and keep all the rounds on target at realisitic distances (10-25 yards) The technique is also very simple to learn and master, and enough so, Ive taught kids and non shooters to do it and usually in just a couple of mags.
Part of this too, and contrary to what you so often hear, is understanding that you arent going to be using FA much past buckshot range, if youre serious about using it for any kind decent precision.
Guns without a stock or some kind of brace, like a fitted sling, are a bit of a different critter, and especially things like the MAC's, UZI's, etc, that have their pistol grip amidships on the gun. They can be flat out dangerous if you dont know what youre doing. Those guns want to rock up and back at the grip, due to the bolt going back past it as it cycles.
Extend the stocks, and they too are fairly easily controled.
I shot this at 10 yards with my SWD M11/9mm. Thats two 25 round mags, one pull of the trigger each (full mag dumps), and total time was right around 3 seconds.
View attachment 927614
This is the gun (bottom), and how it was shot.....
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Now, just to be clear, this was shot to simply show that you can control the gun and dump the whole mag, and on target, and in no way is how the gun would normally be shot. That gun has a fast cyclic rate, about 1200rpm, and the shortest burst you usually get, is around 5 rounds.Still, thats how it would normally be shot. Point it at the target, and give it a quick burst.
The MP5 (and a lot of the older open bolt guns) on the other hand, will easily let you squeeze off one round "bursts" if you desire, and 2-3 rounds is usually the norm. I used to shoot my MP40 at 100 yards, squeezing off one round at a time (the MP40 is an open bolt, FA only gun), with no trouble at all, and consistently make good hits with it.
If good old Ronnie Ray Guns hadn't screwed us back in '86, a lot more people might have had a chance to get to experience these type guns. Then again, even back when they were cheap and plentiful, most still hade very little exposure to and/or experience with them, and the misinformation about them was just as rampant.
Too bad. They are a lot of fun, and in the right hands, can be a very effective weapon.