; Spot-on, Mike. About all of my guys could do it in 3 to 3 1/2 seconds. I practised more than they did as my practise ammo was free - lots of it. 4 days on, 4 off left lots of time to shoot. Actually, I managed this with an old JC Higgins, single rail and vent rib I'd shortened to 22" barrel. I was in the Force (RCMPolice) at that time. I practised with trap loads, then moved to buck and slugs after getting it to sing. The M870's we used in the Corrections branch seemed to work a bit smoother, but were a bit lighter than the Higgins. It was a tradeoff. The most fun was the rack of six steel plates I built for my litle combat matches between my guys and the local detachment. The plates, being much smaller than a silouhette demaned tighter control. 3 empties in the air was a rule. That happens and the time shrinks to 2 seconds for 6.
: It's totally a matter of timing as the slide must lock before you can pull the trigger. Pull it too soon and the gun won't fire when it's in battery. Both the old Higgins and the newer (1970's M 870's) worked well in this type of shooting.
: Once you're 'primed' the recoil of each shot helps stroke the slide back. Bringing the barrle back on target out of recoil, slams the trombone back, chambering the next. It isn't a consious working of the action, just bambambambambambam. The rate of fire sounds similar a WW1 airctaft machine gun with interuptor gear, but is actually only 180 rounds a minute.
: Three of us were out on the jail range practising with the Rem's one day, and the inmates thought I'd inventoried a full auto 12 bore machine gun for tower duty.
: I rememeber seeing the run by Ad Topperwien (or some other MFG'r Pro on the clays with a M12 when I was a kid. This was my inspiration, first with the JC Higgins, then with the m870's, afterall, it's only timing with the non-slam-fires like Ad used. Of course, the same clay thrown stunt is done today by several shooters- mostly baby boomers, of course.

: This all sort of reminded me that when one of "us" was in the towers, the inmates didn't even look at the fence.