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.
