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The model and caliber of the rifle is found on the barrel stamp. This appears to be an M96 Swedish Mauser with a 6.5 x 55 caliber. The Swedish Mauser rifles are well sought after by hunters because they are accurate to shoot. The M96 is a service rifle that very well could have been used as a sniper rifle.
Finding parts for these rifles can be hit or miss. Your best bet would be to do some internet searches for these parts or visit a local gunshop to see if they have any industry connections.