What calibers can I just do a barrel swap on? And why do you consider it just a parts gun? I was planning on keeping it the way it is and just mounting a scope on it.
Like 44AMP said, it is a parts gun because it is assembled from mismatched parts. This happens when rifles are disassembled and the parts are thrown into separate bins for later use. The parts are still good, but collectors are looking for matching parts guns.
You can rebarrel easily to just about any cartridge that is bsed on the 8X57 case head size, which includes many of the most popular cartridges in use today like 22-250, 243, 6mm Rem, 250 Savage, 257 Roberts, 260 Remington, 7X57, 7-08, 308, and several others. Cartridges based on the 30-06 have the same head size but may be too long fthe magazine box.
You can just mount a scope and shoot it if you want, it's OK.