I think some (or all?) of the the B&P short/low pressure loads do not conform to the Gordon System, but I also don't think it makes much difference in practice. Need to read the fine print for each load, as I recall. I started using B&P in my Brit hammer gun with laminated barrels, and they seem to work just fine. Bought some for a 16ga Damascus hammer gun, but have not shot them yet. B&P seems to have a definite price advantage over the competition if you catch their sales and get their free shipping. RST is the most flexible and the most genial.
There are also Kent Gamebore short/LP loads, but can be hard to find and expensive. Galazan used to sell them. Armusa (Spain) makes some nice short/LP loads, but no current U.S. distributor that I know of.
