Probably not much. The problem with the heavier powder charges is that you start getting a higher percentage of powder that gets burned after the bullet leaves the muzzle (where it doesn't do any good and just creates more muzzle flash). You also start to loose accuracy. A typical muzzleloader that produces 2" groups at 100 yds with 100 grns might see 4 or 5" groups when you go up to 150 grns.
Thanks. What do you think my effective range with 100 is? I am using a Leupold with BDC type reticle. I let a buck walk todayy at 160 yards. I am comfortable with the distance if the gun can produce it
I use a Hornady SST 250 grn which is the exact same bullet as the T/C Shockwave (Hornady makes the Shockwave and just puts a different color tip on it - the Hornady branded bullets are way cheaper) and 100grn of 777 Loose powder. Sighted in about 2" high at 100 yds puts me dead on somewhere around 150 and about 2" low at 200. I'd feel comfortable out to about 250yds (where the holdover would be about 5").