Bought a knight disc in 45 cal a few years back,it had a 1:20 twist and was pretty hard finding the right bullet and load for but finally found one that shot around an inch @100.the first day of that years season I took one at 170 yds with it.
The load was 110 gr,pyro-select and a 225 gr power belt.
Sold it to my brother and he tried to get it to shoot different bullets but didn't do well he sent it back to knight and they put another barrel on it (believe it was 1:30 twist,but not sure) He took 2 deer with it the following yer but don't know what bullet he used.
I would try the 200 gr sst or shock wave and 100 gr powder.Or even the power belts I think they have 3 different grain sizes in 45 cal.