I bought a set of brass punches from Harbor Freight years back. When I opened them up my first reaction was that they were too big - I was wrong. I use one with a 12 oz. ball peen. Remove the forearm and put the barrel in a padded vice. I tape the barrel around the dovetail with packing tape to protect it. Skip this step and you will regret it. Get a good grip on the punch and hit it hard. Pecking away at it leads to damage.
It gets easier when you've done a few.
