I have a thunderhawk great gun 50 cal. wood stock
Iwill say it will shoot any type of sabot you run down the bore .
The barrel on mine is tight so .502 bullet @sabot wil load with no problems
My powder of choice is triple 777 3F and RWS1075 number 11 caps
The nipple that works the best are the t/c flame thrower
I load 90 grains of powder and a bufalo SSB 325 or 375 Gr. bullet/sabot
The only draw back is it will not shoot a conical bullet to save it life
The base mount yes only 1 scew in each to hole it to the top of the action @ it will burn the bottom of the scope tube on the open breech
I will say i been out in all weather condition with the thundehawk and it has never let me down