Swiss and T-7 3fg are about identical in performance.
The rouble come is with acuracy.
I managed to get 35 grains of T-7 and Swiss 3fg in my Pietta Rem '58 .44 clone and velocities ran near 1100 f.p.s with round ball.
However accuracy was around 6" at 25 from a solid rest, kick was noticable but not punishing, caps simply vaporized and muzzle/cylinder blast was something to behold.
30 grains of milder Elephant gets me in the 750 f.p.s range with r.b. and accuracy can be wonderful.
My best, once and once, only was 1" at 25 for six shots.
Most groups with the milder load run 2 to 3" with 2" being normal and in my opinion, quite good.
Bear in mind this particular Pietta is the S.S. with adj. sights.
Hardly authenitic but just as much fun.
Really I don't consider any cap 'n ball revolver deer worthy by any stretch.
Maybe as an insurance shot, or to distpatch an immobile wounded animal, but as a primary hunting weapon?
??
Please consider the lowly roundball at 750 f.p.s. as a PEST round only.
I've shot one fox squirrel and one raccoon with the Pietta .44 and the 'autopsy' showed almost NO wound channel, very, very, little tissue disruption, just a small hole in and out.
If deer hunting with such an arm one would have to center shoot the heart, break the spine,(iffy there) or brain the thing at 20 yards or less.
Please think about it and do your own pentration and accuracy tests.
Keep us posted as your results are interesting.