Wow!  Nowadays, Lee Navy rifles are expensive.  Makes me curious about the details of that disaster.  Good thing the guy survived.

I searched the Internet for the $23 paperback, which I should have bought during my initial search.  Instead, I found this:

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Military pattern rifles were produced throughout the civilian range of 10000 to 15000. The earliest production rifles conformed to first contract US Navy specifications. Most, however, had the latest Navy improvements: a gas shield machined as part of the bolt rather than pinned and brazed on, a sighting groove in top of bolt, a low bolt stop, a roller firing pin lock and sometimes a hardened screw on the side of the receiver for the Navy extractor to contact.

The later production rifles reflect the improvements Winchester implemented in response to problems of extraction and gas leakage. A number of rifles, both military pattern and sporting, were noted as “A” model. This referred to the front-mounted short extractor spring, bolt with two gas holes on top, floating firing pin, and gas vent on the left side of the receiver. Some rifles are recorded as “Style A Except Extractor & Spring last Navy style”.