Here's my .58 Huntsman:
1 turn in 66", good results with 80-100 gr. powder loads & PRB... never tried minies or maxis.
Pre transfer-bar action (Ser # AM)
Push-in breechplug that easily knocks out with ramrod when action is open.
It came with a #11 nipple, but is easily converted to 209 (Hubbards) or musket cap (T/C) ignition which eliminates hang-fire risks,
AND the Huntsman's fat firing pin works flawlessly on either of those primers
I also modified the forward end of the plug for better seal of blowby from the standing breech.
NEVER had the breech open on firing.
The original '70's era .45 cal, .58 cal and 12 ga. Huntsman bbls. were all of that narrow lug & correspondingly narrow frame mortise design.
Re-check this thread for more:
http://www.gboreloaded.com/forums/index.php/topic,133215.msg1098502966.html#msg1098502966Steve