Yesterday I bought a Smith and Wesson 67-1 38 special with a 4 inch barrel. the serrial number is 28K7278 marked both under the grip and in the cut out where the ejector rod slips in when the cylnder is closed. can anybody tell me how old my gun is? can i shoot +P ammo out of it? I paid $300.00 for it and have included two pictures. Did I pay to much?