How old are your pellets? Even a brand new box, 2 Triple Se7en pellets is only the equivalent of 80-85 grains loose Triple Se7en it Blackhorn 209. If the pellets are a year old, because nobody wants to throw them out, your charge might be much less in velocity. Pellets start absorbing as soon as they are put in the box, because the box itself is not sealed. They wrap a partial piece of shrink wrap to keep the box closed, but it doesn't seal out moisture. The best thing you can do for pellets, is vacuum seal them as soon as you buy them, and make sure you are getting new stock that was just made. Lots of places have pellets sitting on shelves for years.
How far are you shooting your animals?
I ask, because I have liked in the neighborhood of 40-50 animals with all varieties of Shockwaves, SST's, and FTX's. That includes all the .50 cal saboted 200, 250, & 300 grain Shockwaves and SST's. The .45 cal 200 grain shockwave and SST. 265 grain FTX in Harvester green crush ribbed sabot. 20 ga 250 grain SST, and 250 grain FTX in .450 Bushmaster. Never had one travel over 60 yards, and several DRT. From 15 yards to 115 yards, and never had one that I considered a failure. All showed signs of expansion, none penciled through or grenaded. No deer lost.
Not saying they are the best bullet, but all were through the boiler room with load's to do the job.
All pass throughs, but one 200 grain on a mature whitetail at 115 yards. Black Mag'3 powder. Bullet punched through both shoulders and was found under the hide in the off side shoulder. IIRC, it was 135 grains. Bullet below.
My Optima Pistol even puts them down quick with 80 grains by VOLUME Blackhorn 209 under the 200 grain Shockwave, 1510 FPS @ 10' from the muzzle. Shots kept under 75 yards with clear evidence of expansion on the exits. I documented this one from the first year @ 65 yards. Traveled approximately 25 yards after the shot, and was graveyard dead when he flipped over backwards. One of the quickest kills I've ever witnessed, bow or gun.
Blood trail.
Entrance .40 cal.
Internal damage. Plumbing from the top of the heart pulled into the exit.
Exit is over 2x caliber, .80+ cal.
Works for me!