Look inside the receiver, along the rails that the bolt head rollers contact. Check for indentations to the inside of the rails, either near the trunion or the real of the receiver. Check the barrel for pitting, and worse, a bulge. Bolt gap can be addressed, usually by changing rollers to a larger size. Trigger group and buttstock should go on and off easily, and hopefully you won't need to hammer out the buttstock pins, they should install and be removed by the fingers, although may be tight.