I have the JCWhitney "professional" 3-arm puller and it works just fine.

The secret is to have the center bolt out nearly all the way and tighten down the lug nuts at the studs until they are "fairly close" to the drum, Then pull on the assembly to see that is is centered and perpendicular to the drum. If not, loosen or tighten lug nuts until it pulls up on all evenly when you snug down on the center bolt. Pulling even slightly off-center will make the job miserable and increases the chances of distortion.

My particular puller came with a dog-bone shaped wrench intended to be bashed on. Light taps until it has good pressure on it and then a few solid whacks (and it it hasn't slipped) followed by a couple he-man swacks. I use my 3# short handled machinists hammer.

Having the brakes on will most likely distort or damage them when it finally lets loose (or the WC or the adjuster or...).

I use one hand on the hammer and another on the drum to keep it from spinning... a little turning in my hand is no big deal. For one, I wrapped a few turns of rope around the drum, inserted a bar and tightened it up by twisting and then stood on the free end against the ground.

--
Mike!