A Westernfield M72 (actually a M72C) is a Mossberg Model 472. You might try http://www.krausebooks.com/category/firearms_knives for disassembly instructions for the Mossberg 472 in the Gun Digest Sporting Rifle Assembly/Disassembly book.
I recently bought a mossberg 472 30-30 for 285.00
The western field (montgomery wards) model 72C was made by mossberg arms company.The mossberg model 472 is the same as a western field model 72C.
Marlin made the 336 for Western Auto Revelation 103.450 & .451. mossberg also made their model 472 lever gun for Western Auto Revelation 205.
100-340 or so
You have not asked a question. Yes, the lever action 472 was a 30-30 rifle, similar in many ways to the Marlin 336, made in the 1970s for a few years- at least 3 different models, value, based on condition, may range from $150-$250.
Do not attempt to use other than a Mossberg bolt made for that rifle.
50-150 or so
A Mossberg 22 rifle such as the Plinkster depending on the condition is worth around $150-200.
There are no public SN records- but your rifle was made for Western Auto by Mossberg, and is their Model 472. That model was only made from 1974-1979, when it changed to Model 479.
It is the rifling in a mossberg rifle barrel.
Your rifle was made for Montgomery Ward stores by Mossberg, and is a Mossberg 346K. You can check with a gunsmith, or check the website for gunpartscorp (look under Mossberg). Havlinsales also stocks many Mossberg parts.