what size brass hammer

An 8 oz. should allow you to get into plenty of trouble.......... A 4 oz. is nice to have as well.

An 8oz. steel ball peen is what I use the most. You are hitting the punches, so no need for brass.

I have several sizes of brass hammers, also a couple with replaceable plastic/brass faces. Don't hit a steel punch with a brass or plastic hammer, though; all you do is chew up the hammer needlessly. Use a regular hammer for punches.

Jim

For pin punches i would suggest a 4oz ballpein hammer.

Plastic will be better than brass. No steel at all. Far too much risk of damaging things like muzzles. Better to bang up a plastic hammer than damage the firearm.

I have plastic hammers , a very old leather hammer, and a nice little brass hammer that has a double face. The other face is steel and a soft brass punch is stored in the handle. If it's still offered, it was sold by Lyman. That was maybe 25 years back.

Brownells has a steel face for their replaceable face hammer, usually seen with brass and nylon. But it costs $10 which would get you a small ball peen at Ace.

mfer

What kind of pistol work? I would pick up Patrick Sweeney's Gun Digest guide to Pistol and Revolver gunsmithing as he lays out the basic tool set and explains the whys of his choices. He also does a good job in separating out what an amateur should be capable of and what jobs are best reserved for advanced hobbyists or skilled gunsmiths.

There is a reason that Brownells has pages of hammers and punches. Different jobs are best served by different tools--you can try using just one hammer for example but it will be optimal for some jobs and sub-optimal for others. You can say the same about punches as well. If you asked me in general, what sort of punch and hammer should be bought, I would ask you what task that you plan to do.

One last thing, easily overlooked, using a hammer and punch requires eye protection as metal splinters can be propelled at relatively high speed when you are hammering on a punch and a pin. If you wear eyeglasses, be sure that they are impact resistant and cover the eye socket thoroughly.

Good luck and be safe.

I have a 4oz with several punches in my range bag.
Dan