Try e-gunparts.com
Pull the bolt up and back, then while squeezing the trigger pull the bolt out the back of the receiver. Put it back in the reverse order.
The Winchester model 310 and 320 were made by Winchester from 1972-1975.
I purchased the same model and calibre and it had a bit of a storage make but it was fixable and it was around $500 with out scope just open sights.
It may be a bolt action Mossberg model 321-320
It was made by Mossberg around 1930 plus a few years. It was a low budget bolt action rifle Mossberg model 321 or 320 under the Western Auto name
My cross reference show this as a Mossberg model 321 or 320 Bolt Action. I suggest you find a "2010 Standard catalogue of firearms" and look up the photos. Look under Bolt action rifles in the Mossberg section.
Your Winchester model 320 which was made from 1972-1974,will bring between 150-250 dollars for a rifle showing between 60%-90% of its original finish,and a good bore.
you un bolt it
The action was manufactured in Australia circa 1973/74 by Adelaide South Australia based company Sporting Artms (www.sportco.org.au) - Winchester USA purchased 25,000 actions and fitted barrels/stocks in the USA. Aussie dollars about $300 - $400
Yes they do have same bolt pattern . The offset might be off a millimeter or 2 but you cant tell.
50-175 usd
P=$20 F=$45 G=$65 V.G.=$80 EX=$100 It's a mossberg model 320 or 321 Bolt Action