I have a 444 Marlin pistol barrel for my Encore with a factory installed brake on it, andI'm in love with that thing!! I'm like a little kid everytime I think about shootin it!
I don't have it scoped at this point but I have no problem keeping 4" groups at 100 yards with the open sights and it has no bullet drop at that range. It does pack a punch, but I've shot 20 rounds through it in an afternoon and it wasn't too bad.
I would have nodoubts in my mind if I wasaiming at an elk or moose out to 150 yards, if I scoped it maybe even farther.
There are so many options for this round if you reload, becauseyou can use any ofthe .429 bullets for the 44 mag in it. As far as factory loads, there are only afew, I've shot a coupleand they both shoot great out of my pistol.
I know this wasn't one of your choices on your original post, and I don't believe that this is available in SS, even from the custom shop. (I may have a little hillbilly in me but I put the blue barrel on my SS reciever and it looks fine to me

My vote from the choices you gave us would be the 45/70. It won't hurt you near as bad as the animal you just knocked off of it's feet with that powerhouse!!
I am very interested in the 375 JDJ as well but as you guys mentioned, getting ammo and components at this point is a little tough, so maybe in a couple years I might try one.
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I've been accused of favortism

here are my favorites:
Mathews Z7
T/C Encore 209X50
-Leupold 3-9X40
Winchester Super X3
Winchester Model 94 Big Bore 444 Marlin
Winchester Model 70 300 Win Mag.
-Leupold 4-12X40
Ruger Super Blackhawk 44 mag.