Unscrew the large (largest and most obvious screw on the entire gun - located on the receiver) take-down screw and pull it out as far as it will go. It won't come all the way out. Carefully but firmly pull the barrel section from the receiver and butt stock.
You need a manual. Contact Winchester or find a gunsmith and ask for help.
The Model 77 Winchester will fire either long or long rifle cartridges. It is not chambered to fire short .22s cartridges.
don't take down a Winchester model 52, the way they bedded the rifle was a mystery. It may never shoot the same if you take it apart.
Best left to a factory trained gunsmith
You should be able to find a assembly-disassembly guide for your Winchester model 37 on E-bay.If not you may to need to visit a qualified gunsmith.
You need a copy of the owner's manual for your rifle- trust me- parts of the bolt are tricky. You can get a copy for free from Winchester is you are in the US. The link below will take you to their order form on their website.
hit it with a hammer
You can get the manual from this page with some basic info. http://www.winchesterguns.com/services/index.asp
take it to a gunsmith
Take it to a gunsmith for exact measurement
All Winchester model 12's are take-down designs. Winchester made a model 25 which is solid frame and very similar to the model 12.
Best to ask a gunsmith for help