But today we have loading for both LR & Mag designed for short pistol barrels. The LR does it better then the Mag with the shortest. But after about 3.5" the mag out paces the LR.
With standard LR offerings 16" is optimal and longer can actually be lower velocities. Hyper velocity offerings can see marked gains in velocity. Magnums dont see super velocity gains. They read/advertise 2200fps+ but usually dont hit those highs. My 24 Savage only bears my 22" barrels slightly.
CW