I use a Wilson depriming tool. The Wilson looks like a punch with a longer end that knocks the primer out with a light tap of a mallet. It's about 20 bucks.
I sit on the sofa with a block of wood, the depriming tool and a little mallet and wack away.
Might check out Neil Jones Custom Products Universal hand decapper.
It's universal for two common different boltface diameters, and extra bases are available for stuff like Magnums or 338 Lapua.
Lightweight, strong enough for the job and you can deprime on the couch, in the car, or even on the toilet if you so desired.
Been using the same one for over 20 years now, and my great uncle was using it before I got it. Just give Neil a call and tell him what cartridges you'll want to decap, he'll send you what you need.