Rocketman, O.K., I'll give to you the possibility that the wad skirt may still seal the bore in the small jump from 12 to 10 ga. or 16 to 12 ga. How ever I'm pretty certain that gas leakage would occur in the jump from 20 to 12 or 28 to 12 ga. I think even in 20 to 12 and maybe 28 to 12. I'll check that again against a wad skirt. But even where blow by does not take place, it seems to be claiming a physical free lunch to assume that increased force on the wad base would magically occur just by the area of the wad base instantly increasing in size during the transition from Gaugemate to nominal bore size. In the F=PxA calculation, if the area increases and pressure is constant, force would somehow increase just from the wad entering the larger bore. If the wad base expands to fill the larger bore, then, yes, the force increases. This is how a small hydraulic piston raises a large load on a bigger bore cylinder. If that were the case, why isn't every shotgun maker taking advantage of this? There is no "free lunch" here. A given charge of powder contains sufficient energy to accelerate a given payload to a given velocity with the diameter of the launch tube playing a smaller role than most would expect.
So are we to believe that just because the wad skirt of a 28 ga. wad can be flared out to .729" or so, it will still contain perhaps 9000 p.s.i. without that skirt blowing forward and losing its' perfect seal? That would be some tough skirt. Whew! I will still contend that even if that wad could contain the pressure, as the area almost instantly increased, the pressure would have to drop and force would remain equal (assuming zero blow by). Anything else would absolutely be claiming a physical free lunch. Are you saying that if we have, for example, 9000 p.s.i. gas pressure contained in a one cubic inch cylinder and we increase the volume of the cylinder to two cubic inches, that we would still have 9000 p.s.i.? Certainly not... not without adding more gas or superheating the same gas in the doubled volume. Now, I wish I knew how to put your following statement in red letters: "If the wad base expands to fill the larger bore, then, yes, the force increases. This is how a small hydraulic piston raises a large load on a bigger bore cylinder." Whiskey Tango Foxtrot. No, no, no. Huh uh. Nope. In a hydraulic pump, be it a simple hand Porta Power type pump, or a multi stage variable displacement rotary piston pump, the small diameter pump piston(s) driven by hand or motorized force displace a volume of relatively incompressable oil equal to the bore radius squared times pi times the stroke (length). This volume of incompressable fluid under pressure acts upon the base of the larger cylinder piston and moves it a porportionately shorter stroke. The larger the cylinder piston, the less one stroke of the pump piston will move it. Again, there are no free lunches here. We are talking about x grains of powder acting upon y dia. wad base containing z ounces of shot. Ain't no quantum mechanics where light speeds up, quarks and muons become charmed, and time goes backwards.
