First decide weather your preferred factory load does what you need, only change it, if it does not.
Quite safe to knock projectile out with a kinetic puller ( just as Cordite says), it is a normal practice. Then use a regular seating die to put it back where you want it. If you get a bit excited and knock the projectile clean out, you just put it back together again (assuming your hammer is not full of other crap). Loaded projectiles that have sat for a long time (years), benefit from a smack and reseat if you were a target type shooter.
A tactic I have been guilty of from time to time with factory loads if forced to go down that route, is to pull the projectiles, measure the powder charge, cross reference load data and sacrifice one round for it's powder and use that powder to "top up" the other 19 cartridges in the box. The factories generally lie about velocity.
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