First off, Welcome to Graybeard.
Now for your question, 100 gr. is sufficient in my opinion. I shoot my 45-70 with only 64 gr. of black powder in a cartridge past 200 yards. I know it is not a muzzleloader. But in my Encore .50 cal, I only shoot 100 gr. of triple7. I think the 150 gr. is a bit much and I personally would not use it for deer. Know if I were going after Elk or Moose I would work up to 150 gr. of triple7 and a good bullet for penetration. But it is not needed on deer size game IMHO.
You may also want to post this in the MODERN Inline Muzzle Loading Rifles & Shotguns area. You might get more replys there. :grin: