Let's talk about the FIRST high capacity, rapid fire gun. We'll just the GURPS numbers for RoF and reload times.
It happened almost as soon as there were guns. Someone added extra barrels. Heck, on a wheel-lock that meant adding a whole extra gun, lock and all to a single stock.
Then they developed means to load shots one behind another and have multiple locks firing the muzzle-most charge first. This didn't work very well, but shoot more shots faster has been part of gun development since the beginning.
The pepper box is our next stop on this journey. Many of them are even double action!
Colt's revolver is simply a very refined pepperbox.
Let's look at it. If you're really good at it and have paper cartridges ready it takes about 20 seconds to reload a muzzle loading pistol. So you get less than three shots a minute (2.86).
A pepperbox will take about the same amount of time per barrel to load, but you can empty it in about two seconds! It's a slight reduction in rate because the loading is more fiddly, just less than two rounds per minute (1.98), but you get a flurry of six right off the bat! And you have to carry a single 1.8 lb gun instead of six THREE pound guns to get that flurry.
A caplock revolver takes less time to reload per cylinder because the rammer is built into the gun. A single action gun is slower to fire than a double action pepperbox, but almost six shots a minute now (5.45)!
Now we introduce cartridges.
A gate loaded revolver like a Colt Peacemaker can get about 10 rounds a minute. Break-open guns like a Schofield can get 15.
There were two goals in the development of the ammunition from matchlock to wheellock to flintlock to caplock to cartridge. First was improving reliability second was improving rate of fire. And since a gun that doesn't go bang has a rate of zero, reliability has an effect on rate.
The next big change comes when we start harnessing the wasted energy of the shot to perform functions that muscles used to do.
That's how we can get a 1911 with about 78 shots per minute (78.75).
All of the above are NY legal.
A Glock 17 ups the rate to just under 118 rounds per minute (117.69).
Now, let's talk about rifles.
The same pattern evolves here.
The muzzle loading guns pretty much parallel pistols.
A Brown Bess can put less than one round a minute down-range (0.68).
A P.1853 can get almost 4 (3.75).
But then we get the
Then we get metallic cartridges. A Spencer carbine upped it slightly to 18 or so (18.26) and had seven on tap before you needed to reload.
Remember the French? They came up with the Kropatschek which got the same 15 shots per minute as the Prussian gun, but had 8 shots in 8 seconds before you had to start loading.
Not to be outdone the Germans came up with clips to speed up the reloading process. A five shot Mauser can get off 37.5 shots per minute.
Then we harness the waste energy and get the Garand which can propel almost 85 rounds per minute (84.71). But the Garand isn't NY legal... OK, how about a Remington Model 8? It's a five shot, clip loaded, magazine fed semi-auto: 64.29 shots per minute.
With the advent and adoption of detachable box magazines for rifles we get guns like the FAL which were almost always shipped as semi-automatic only and can get a rate of fire around 124 rounds per minute (124.14).
It's not until we back off the "effectiveness" of the cartridge that we can get a rifle that can utilize automatic fire and the StG.44 can get 266 1/3 rounds per minute.
It seems like I am making the gun-grabber's point here, doesn't it?
What these numbers are is pulling the trigger as fast as you can and stuffing in new rounds as quickly as possible. This is not aimed fire! Hardly any of the 266 rounds your SturmGewehr sprays will hit what you were looking at. If I slow down and AIM with that Remington, I am down to 23 shots a minute, but I am also up to very close to 23 HITS. Spraying with an assault rifle is less than half as likely to hit a person at 50 yards per second of fire and is dumping eight rounds a second in their general vicinity. Basically 32 times as many shots per hit.
Slowing down and carefully aiming with our StG.44 like with our Remington? 28 shots per minute. Despite having SIX TIMES the ammunition capacity!
That's why the size of the magazine doesn't matter. Especially since there's fewer than 10,000 assault rifles registered in civilian hands.