Don't know if you've seen this one,
I suspect you have.
The mount is as interesting as the gun.
And I agree with Othias.
The Pederson probably would have been a fiasco.
https://www.youtube.com/watch?v=GPC7KiYDshw
I haven't seen it yet but I'll add it to my list. I'd love to be able to visit some of the various ordnance museums. The U.S. Army Ordnance Museum at Aberdeen Proving Ground used to allow civilians to tour it, but it closed down and re-located to Fort Lee, Virginia. I don't know what their policy was there, or will be after COVID. I thought it was kind of funny when the MOAB came out and people started calling it the Mother of All Bombs. It weighs less than half of the T-12 bombs developed at the end of WWII. They had the casing from one standing on its nose outside the museum at APG and they took it with them during the move. 4,000 pound bombs were nicknamed blockbusters because one of them could wipe out a city block. This bomb was almost 11 times bigger so it got the nickname super-blockbuster. I don't know how many city blocks it would take out.
The super blockbuster, for when you really need to f**k s**t up! Wikipedia calls it Cloudmaker but I don't recall ever hearing that before. It doesn't say how much of what type explosive it has, but it weighed 43,600 pounds, and they say the MOAB blast yield equals 11 tons of TNT. My best guess would be that they have similar explosive forces, but the T-12 was an earthquake bomb and would be 100 feet or so underground when it went off, not up in the air. The Massive Ordnance Penetrator bunker buster weighs 30,000 but Wikipedia says it only has 5,300 pounds of high explosive. The old blockbusters were 75% explosive but that's only 17.67% explosive.
They had a line of vehicles up and down the road on "tank row" at APG too, and I think I read before that all the tanks were moved to the armor center at Ft. Hood, Texas. I got to walk around an AH-56 Cheyenne attack helicopter outside the museum that was developed for, but not adopted by the army. It had a pusher prop on it to make it go faster which was something I never heard of before. "During vertical and hovering flight all power was applied to the main and anti-torque rotors, while during forward flight all but about 700shp was shafted to the pusher propeller. In forward flight lift was generated by the stub wings and windmilling main rotor. In 'clean' configuration the AH-56A was capable of sea-level speeds in excess of 275 miles per hour." 244 mph according to Wikipedia, with a cruise speed of 224 mph, and rate of climb of 3,000 ft/min. So in forward flight it would more or less fly the same way an autogyro does. I think that contributed to its 1,223 mile range. It might have revolutionized warfare. It was supposed to have a nose turret with a M129 40 mm grenade launcher with 300 rounds, that was designed to be interchangeable with another nose turret with a 7.62×51mm XM196 minigun, and also have a belly turret with a XM140 30 mm cannon. 21 years after the Cheyenne's first flight, the AH-64 Apache was adopted. The maximum speed is 182 mph with a cruise speed of 165 mph, and rate of climb of around 2,900 ft/min. It should never exceed 227 mph under any circumstance, like a steep dive. That's about equal to speed the Cheyenne would be able to cruise at all day until it ran out of fuel. Maybe we adopted the wrong helicopter. I guess that would be obscure gun-adjacent stuff.
https://en.wikipedia.org/wiki/T-12_Cloudmaker https://en.wikipedia.org/wiki/Lockheed_AH-56_Cheyenne