I know what you are talking about , But don't know the answer
But I hunt ducks with 2 muzzel loading shotguns
1 is a side hammer TC and the other is a inline Austin & Halleck ( sp ) , both are of modern steel and have choke tubes
The TC is rated for 120 gr and the A&H is rated for 150 Gr of black or a sub.
In the TC I load 100 gr ( volume ) of 777 , a 1/2" wad 1 1/8 oz of steel shot and 1/2 of another 1/2" wad for a over shot wad
This is a nice all around load for upland and ducks & geese depending on the shot size & choke ( mod or Ic normaly )
In the A&H I load 120 gr of 777 , a 3" steel shot plastic wad , 1 1/4 oz of steel shot and a 1/2 of a 1/2" wad for a over shot wad
This is more the high proformance load and the recoil in a light gun enough , as the 150 gr loads are a little more than I enjoy
I shoot a LMchoke tube normaly
I am not sure what gun you are shooting
But be sure to not shoot a load hoter than it is designed for
Also not all muzzel loading shotguns are rated for steel shot
For those guns , Bismuth or Nice shot is you only sub's and neither are cheap
http://www.ecotungsten.com/online-store.html
Also Bismuth shot is getting hard to come by as the US producer closed this year
The plastic shot cups ( wad ) produce a tighter pattern
But leave plastic in the barrel and cause tough loading after a few shots
So I run a bore brush thru the barrel as needed
I would start with a 80 gr load and 1 1/8 oz of shot
And increase the powder to the max of the gun as you pattern the gun
I found a max load didn't pattern as well as a slightly reduced load
John
steel shot loads for 12 ga black powder shotguns?
