That's exactly what I've been doing a lot of lately, g. I stand or sit, use a dumbell that's heavier than a gun, like 2.5 or 5 lbs, and practice repeatedly bringing it up "on target" (some spot on the wall). For variety, I use a 5 lb plate instead of a dumbell. That makes it unbalanced, puts more of the weight out toward the "muzzle".
I also practice similar but without a weight. Just my hands in a gun grip fashion. Practice repeatedly putting it on the same horizontal line around the room, as if I were shooting plates.
Sometimes worry that it looks a little weird to other gym goers. I'm sure I've had that muzzle safety drilled into me. I literally can't bear to bring my finger on target when another person walks through my field of vision.
Sgt Lumpy