I shoot the Barnes Spitfire TMZ and spent a ton of time dialing in my setup with BH-209. I found that there is not much of a ballistic drop difference between the 250 gr and 290 gr when using 100 gr by volume of BH-209. I cannot say what the difference is at 120 or 150 gr by volume. I personally wouldn’t shoot anything above 120 gr out of my TC Omega muzzy.
I used 100 gr by volume of BH-209 because it got me a muzzle velocity of 2000 fps +/- 50 fps regardless of which of the bullet weights I used and since my son is small framed, I wanted a load that he could handle without flinching. I went all out and verified using a chronograph to see how consistent my loading, cleaning, and shooting setup was. Once I got a consistent muzzle velocity, I dialed in my scope with both loads (this was back in 2020) and found I didn’t have to adjust my aim point for the bullet.
That year, I had a muzzy deer hunt right before my son’s muzzy elk hunt. I used 100 gr by volume BH-209 with the 250 TMZ for deer and he used the 290 TMZ with 100 gr by volume BH-209. We used the same muzzleloader and were both successful. I took my deer at 45 yards and he shot his elk at 93 yards.
I’ve attached the ballistic table for both bullet weights so you can see what I was after. That load got me 2.5 inches high at 100 yards and zeroed at 150 so I could pretty much hold the crosshairs dead on out to 150 without thinking about it. My max range would have been 200 yards just due to my ability but I’ve been lucky to get closer than that. Between my son and I, we’ve taken 3 bulls and a mule deer between 2020 and 2023 at 45, 93, 86, and 64 yards.
This year, I had to dial in with open sights for my bull hunt. I kept the same load and adjusted my rear sight to get me at 2-3 inches high at 100 yards. Once I was dialed in at 100, I held about 8 inches high and hit the 200 yard gong, which was plenty confirmation for me.
Good luck!