I have shot about 12 turkeys with the 12 gauge muzzle loader. I think it is the only way to go.
I used a 12 gauge flint that I built on all but my first turkey. The first bird was a CVA side by side. That gives the opportunity of two shots, although I have never needed it.
I use 90 grain of ff a plastic shot cup and equal volume of number 5 or 6 shot.
I have used unslotted two piece shot cups which work well some of the time. The shot may not separate from the cup, like shooting a slug. I have killed birds to 3o yards but most less than 20 yards. I have missed two birds when I feel the shot didn't separate from the cup. I use a standard shot cup now. I used traditional wadding for many years but the plastic shot cups easier.
I use a very thin over shot card.
I have taken ruffed and Blue grouse on the wing as well as Quail, Chukars and Huns.
I bought but haven't used a 12 gauge barrel for my TC New Englander. This gun has a screw in choke. It will take a turkey choke, you must take it out to load