.075 actually sounds high to me. The type of barrel, with or against the wind, barometric pressure , and velocity all affect the bc calcs.
I don't have numbers for you but can measure them here at 3000 ft elevation if needed. In the 20.2 shooting I've done, they were more wind sensitive and had more drop, than the Jumbo Monster Redesign 25.4s , and those compute for me at the 0.051 area pretty consistently.
I'm currently set up only with an LW poly in 22 though. Possibly could drop a 3 groove TJ in for a quick test. Don't have a 6 or 12 groove handy right now...
Bob