GSI the 10grs of Unique and the 250gr cast is plenty flat enough for shooting to 100 yds. With your 7.5 barrel you should be getting 1200FPS or little more.

Use the adjustable sights on your gun to dial in to the yardage you want to shoot at. OR,, Yes you can set up the gun to be "ON" at 50yds and then play, or move to 100yds, or farther.
You stated Practice with CAST and Hunt with JACKETED ? OK then most likely there will be a slight change in adjustment in sights. I wonder what choice of bullet for hunting?

Now, I did not want to go here, but I will for the sake of information.
Shooting a lighter load with less recoil is much more beneficial to the shooter than shooting Full house loads all the time.
I don't remember who it was, that said to shoot the amount of ammo at the same given yardage. In other words:
25yds 25 rounds 50yds 50 rounds 100 yds 100 rounds.
You got the picture, and you even stated that you would like to shoot 50-75 rounds each session. Excellent !!!
But may I suggest that you do this with a load light enough that it will not tire you out or cause your hands to hurt. You do not want your ability to wane or to put it another way,,, You will see your performance drop off after shooting full house loads continuously in a 50-75 round session.
Let me stop here and point out, that when I say, cause your hands to hurt, I do not necessarily mean that immediate pain. The next day or a day after is when your wrist or hand may hurt. I doubt it with the loads discussed, but you also have not been shooting for awhile, and I do not know, what physical condition you are in. LET'S DON'T QUESTION AND ANSWER THIS HERE. Ask yourself, and determine it offline.


So with that in mind you could consider or even use 8.0 grs of unique w/240-250gr cast, and still get 1000FPS more or less depending upon your barrel. I will gladly take that load and shoot at 100yds 200yds and even 300yds. TARGETS only NO GAME!
Practice with those milder loads then step up to the hunting loads when season comes around.

I want to know about the cast bullet you are shooting? Flat base, Gas checked, SWC, LBT style, etc etc.... Mold number or Maker would be nice too.