I’ve never heard of PW Arms before, but a quick search comes up with the following info for them:
8525 152nd Ave, NE
Contact E-Mail: email@example.com
Contact Phone Number: 425-882-1161
Contact Fax Number: 425-882-0487
You could always give them a call or send them an E-mail and see if they can help you.
However, I think you’ll find your rifle is NOT a PW Arms gun… it’s a Winchester.
The reason I say this is that the “PW” symbol on the barrel- which looks like a P superimposed over a W- stands for “Winchester Proof”, and like the Nitro Proof marks found on British and European guns, basically says the gun didn’t blow up when they test-fired it as they left the factory. It’s stamped on the barrel of every Winchester rifle- certainly, every Winchester I’ve ever seen or owned.
Your best bet is to get in touch with Winchester (more accurately, the US Repeating Arms Company), and ask them if they can help you identify your rifle specifically.
They even have a website, which might help you out- it has lots of pictures and information on it, as well.
Hope that’s helpful, and I’m sorry I can’t give you more information… unless you’ve got a picture somewhere you can post!