Look at the pictures here of the forearm. This is what can happen many times, when trying to remove those.http://www.gunbroker.com/Auction/ViewItem.aspx?Item=545281019
Phil, the pins are usually installed from the right side of the forearm. You should drive them back out that side, using the right size punch inserted on the left side. If you don't have a punch, you can use a drill bit. Put the flat end of the bit in the hole and tap the drill point end with your hammer. You will likely destroy the bit, but that is a cheap Replacement, and you'll have the damaged one to use again next time. If the holes are not clear, run a drill bit of the correct size in the exit holes until you touch the pin. Use a thin cloth under the wood to protect it against a firm bench. Once the pins are flush or slightly sticking out, you can hang that pin slightly over the edge of your bench, still on the cloth, and continue driving it out. I've done dozens this way and have never chipped the wood. The key is to clear the exit hole with the drill. Even if the drill bit is a hair larger that the hole to ensure the pin won't grab the wood as it exits.