Load a bullet with a similar BC to the same velocity, and you're good. The trick is to match the trajectory, zero for your practice load and train all summer, then re-zero for your A-Frame load and go hunting.
If you're talking about .308" bullets, then the 180-grain .308" A-Frame has a BC of 0.40. The Hornady .308” 150-grain FMJ (#3037) has a BC of .398—more than close enough—plus it's cheap and available. Match velocities, tweak for accuracy, and you’re done.
You don't need to train with the same rifle or cartridge if the trajectories match. For instance, my 30-06 shoots well with a 180-grain Hornady flat-base spitzer (#3070). I was short on #3070s going into a bear hunt last year, so I did most of my train-up with 168-grain Hornady Boat Tail Hollow Point Match bullets (#30501) in a 308 with a load that matched the 30-06 trajectory with #3070. I left the 308 at home and killed a bear with one shot from my 30-06 at 353 yards.
And telling that story just reminded me to go get another batch of bear-meat sausage out of the freezer.
Last edited by okie john; 06/17/22.