So was the "M40A2" mentioned in both books built by the USMC or was it something like Mcmillan themselves put together?
Others will know more, but I am not aware of anything
official that was called an "M40A2" - but there are pics and anecdotals of prototype rifles from the 1990s with odd-ball configurations that were loosely based on the M40A1 thus folks are prone to call them "M40A2s" - but with different stocks, different scopes, different scope mounts, and even a shortened barrel threaded for a suppressor -
all these permutations were tested, but none were fielded in an official capacity (ie, no technical package was developed, no National Stock Numbers were developed, and nothing was officially procured.) Could the late Gale McMillan have given the USMC some of his newer stocks -
gratis (free) - to test/evaluate in the 1990s hoping that it evolves into a prospective new 'M40A2' procurement opportunity for his company? Absolutely.
Per Jim Land, the M40A2 recoilless rifle was still in USMC weapon inventory, so the M40A2 was skipped over in favor of the M40A3 nomenclature. (Presumably the nuanced difference b/t ordering a "M40A2 rifle, sniper" and "M40A2 rifle, recoilless" might have caused some confusion, and I imagine it would be hard to conduct a stalking exercise if the "M40A2s" that were ordered - showed up on-site in huge crates consisting of 485-pound recoilless rifles...opps.)
Digressing somewhat, but Gale McMillan did offer some 7.62 NATO sniper rifles to the US military in the mid-1980s that were improvements over the M40A1 configuration developed the late 1970s era.
These were not USMC rifles - but were instead purchased by U.S. Special Operations Command (SOCOM) - and are really a different subject unto themselves, but they are pretty close to what is pictured in post #5, but with a slightly different McMillan stock that has a higher comb, and a different camo pattern. (Pic 1 is from Joe Poyer's book,
Collecting the American Sniper RIfle 1945 to 2000, pg 126).
The M86 rifles purchased by SOCOM solved the 3 issues that Gale McMillan had identified by the mid-1980s re the M40A1s: Higher cheek weld/cheek piece was needed, a bipod stud was needed, and a scope mount that accommodated 30mm rings was needed for the new Leupold Tactical scopes.
My understanding is that 460 of the M86 rifles were purchased by SOCOM around 1986 (or so), and they were used by Navy SEALs and perhaps other SOCOM units up through at least Desert Storm circa 1991 (see pics 2 and 3). Again, the M86 is a separate rifle platform altogether and used a special action that McMillan briefly made that was based on the Remington M700, but with various changes. From both a configuration perspective and chronological perspective regarding the evolution of McMillan stocks, the circa mid-1980s M86 fits between the M40A1 and later M40A3 configuration.
Bottomline, me thinks a "USMC M40A2" is a mythical creature based on one or two or three misc prototype, or concept rifles, tested in the 1990s by the USMC, but never officially fielded or officially developed into a Technical Package. That process didn't occur until around 2000 with the M40A3. My 2cts.