At the power level of your intended ammo, you could use those once-fired cases.
If I couldn't find new cases, I would......and have.
If I were looking for 1400--1500fps, I would NOT.......
I have done before exactly what you've considered; I have bought 'factory' cartridges, reduced them to their components, and used the unfired cases (resized, natch)(or on certain occasion, the bullets) for load development.
Tossed the powder.
Seating and crimping the bullet (please note some manufacturers use adhesives to aid securing the bullet) does NOT put similar stresses on the case that firing will.
If using your pull-down case, ensure its mouth is not suspect.
You may successfully trim away its crimped portion without significant change in case volume.
"all my ammo is mostly retired factory ammo"