A couple of points...
Superdomes are a large pellet, so consider other larger sized pellets (Bisley LRG for example, or hobby - but hobbies are also very ballistically inefficient see below)
Superdomes are very inefficient through the air - so even if your FTTs (which are much more ballistically efficient) are leaving the muzzle with 1 FP less energy, at 25 yards there will be no difference, and FTT will have more energy further out.
Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.