I'm looking at buying a pre-Gold Cup Natinal Match. I don't have the serial number, but it's one of the ones produced from '57 to the early 70's. The gun is all original and has barely been shot at all, but was stored for over 20 years in poor conditions. There are some small rust spots on the front of the slide and when I stripped the gun it had some small surface rust on the interior, but nothing major. How much is this gun worth? I noticed the slide was much lighter than I'm used to and I'd heard in the past that these guns were meant for wadcutter ammo. What can you guys tell me about these?