Excellant post PeteM!! I think these .44 cal shot shells was one dead end line of evolution, and what we know as the .410-bore shot shell evolved from the European 12 mm shot shell -- first as the 2-inch with 3/10 ounce of shot then the 2 1/2 inch with 3/8 ounce of shot then upped to 1/2 ounce of shot, and finally the 3-inch with nearly 3/4 ounce of shot.
I was given one of those little H&R 44 cal. shot single barrels when I was 16 by the gardner at the estate my Uncle managed in Palo Alto. Over the next few years I acquired a full box of 50 Winchester Staynless .44XL shells loaded with smokeless powder and a broken box of Peters .44XL loaded with semi-smokeless powder. My Dad and I actually fired a few of those semi-smokeless loads 40 + years ago and they really stink!!
