Give up on the TMKs already. Sometimes barrels just don't like certain bullets. Try the 178 bthp (not the amax, very different designs; also better bc than the 175 smk at a lower price) or the 190 smk. Also, 2650 is just fine for velocity in a 175. If you want better performance, change bullet or caliber. Pick what you want: less wind with more drop, or less drop with more wind- the 308 cannot do both- it isn't designed to. The 243 is, and you pay for the performance increase. The 155 Scenar is also a high performing bullet in 308- it will not give up ground to the 175 smk/tmk downrange.