So both are rated for 150gr charge?
I figure the 26" would still be shorter overall than a gun with a breech or action.
No they are not both rated for 150, but refer back to Keiths post. The only difference in the rifles is 2" of barrel. Some of the older ones, both 24" and 26" had 7/8" breech plugs, since 2005 they are 5/8" plugs. The 26" barrels were the only ones rated for 150 grains.
Here is what my 2003 Owners manual says for a 24" SS Huntsman. These are recommended loads for accuracy. Disregard the .45 caliber information, they never released those.
This is exactly what it says in the Owners Manual, but remember they did not offer the 26" barrel until 2004. 2002 and 2003 were only 24" barrels.
"NOTE: These loads are recommended for optimum accuracy. Exceeding them is not likely to increase performance and can result in higher pressures and unsafe conditions. Do not exceed propellant manufacturers' recommendations. Loads recommended for FFG black powder may also be used for Pyrodex RS on a volume basis. This rifle is designed to use #209 primers."