Take into account that in most cases you may not see a complete powder burn when using 150gr charges. The length of your barrel will contribute more to the potential accuracy of 150gr loads. Most of the first 150gr capable inlines had barrels too short to accomodate (20-22"). Now more and more inlines are going towards the 26" and 28" barrels. A good test to see if you are getting a complete as possible burn is to shoot a round at white paper set about 10-15 yards from the muzzle and fire a round at it. If you see burn marks or even loose grains...that is a sign of wasted powder. I tried shooting 150 grains out of my old TC Black Diamond XR (26"bbl) and noticed 150 grains and a 300gr projectile didn't have much difference in velocity or downrange capability than a 300gr projectile and 100grains of powder. Of course every one is different, but, I would rather make better use of my money than shoot 150grains of powder. The powder I used was Hodgdon Triple 7 FFG. Having said that I am going to a TC Omega (with a 28" bble) to help increase my velocity and down range performance this year over that of the Black Diamond.