As with anything else in history, the reader of text (or viewer of film) must transcend his mind to that time frame to be able to fully comprehend and understand what the intent of the writer or producer was ... but ... that is not often possible, mostly because few use the psyche of "time", albeit, a recent comment written is likely from someone who was alive an kicking in 1938.
Some people have trouble thinking or remembering that prior to 1996 there was no internet to have a wealth of data at the press of a button. The internet did not start to catch on like wild fire until well after 2000. How could that person try to imagine what 1938 was like ?
Then, as with anything else, you cannot believe everything you read ... especially if it is comments made in blogs or threads or specialty forums.
I read some of the mechanics and collectors auto Q&As ... it is amazing how many misinformed people, or people who heard something way back when, now become "professors" of statements that are completely false.
For example, the cylinders on the first airweights would blow out. Yes, that did happen but it was more likely to crack the frame on the underside where the barrel screws in, long before it would blow out the cylinder.
The model 39 with the bad extractors. Yes, true ... but not near as prevalent and re-tellers who have NO idea or have never experimented with a 39 or pre 39.
Again with the story of the 1913, .35 S&W Autos. They functioned fine with the correct ammo, yet, the story handed down was that they all malfunction. Well, they DO NOT (or rarely do) malfunction with the correct ammo.
In my teens, when becoming a scuba diver interested in wreck diving, I wrote letters requesting information on U.S. Naval losses during WWII and geographic location of each loss, to which receive a big fat envelope about a month later with exactly what I asked for ... or, at least, what they were "allowed" to release to the public. This, just a short example of what "research" entailed, not too long ago.
ALL of the above as a prelude to the following:
Putting myself back in 1938, I suppose there were not many opportunities to find or view a 1899 M&P target. I have owned two, I still have one, previously owned by Ed Cornett. Assuming McHenry actually means any M&P (calling them the 1899) there should have been plenty of target sighted 1905/4th changes, while the 1899 was, and still is, rather scarce with Factory Target sights. As is the 1902 (all changes) and the 1905, 1,2, & 3rd changes. Coming up to the 1905 / 4th change, there seems to be enough to go around, most likely from the sheer volume of all 1905/4th manufactured over the 3 or more decades it was manufactured.
Roy Mc Henry's eloquence in responding to this inquirer was less than what I would expect from an educated man but perhaps he was a bit more at ease responding to a sportsman than, by comparison, as if he were the John Carradine character (a statesman / politician) long winded, elaborate, oration in "The Man Who Shot Liberty Valance".
He may have very possibly liked alcohol but unless you, personally, knew the man ... it is an unfair statement.
I also feel very confident that Walter Roper, was NOT an idiot (as mentioned by you know who). I perceive Walter Roper, perhaps as a Doc Emmett Brown in Back to the Future. Could have been eccentric, perhaps, but seemed to really know his shhhhtuff ! All letters I have written by Walter Roper present as a friendly, professional and without a doubt ... written as a dedicated Smith & Wesson employee. Even those he wrote while employed by Harrington and Richardson, he recommends, in a reply to an inquirer, the firearms the enquirer is seeking is best made by Smith & Wesson.
I call that man an absolute Gentleman regardless of who might say what (80 years later) to the contrary.
The combination of Roy McHenry and Walter Roper on their book seemed to be a very earnest attempt to put a assortment of S&W data "out there" that was not available, prior.
Perhaps, looking at it today, it pales in comparison to newer publications like Neal & Jinks, Roy's own History of S&W, and the most current S&W bible: Standards Catalog of S&W by Supica and Nahas.
Before SCSW, collectors mined through articles (hoping they were factual), then jumping through books from Rywell, to Roper, to Mc Henry and Roper, to Neal & Jinks, to Jinks ... just to accumulate a few "scraps" of data they hoped was factual. Roy Jinks "History" was the first S&W book I obtained and read.
I did not discover, until 1990, that post war guns were matte finish from the factory. I had previously suspected they were refinished. I had to find that out by myself just from the sheer number of S&W revolvers I encountered of that period in matte finish, figuring that cannot ALL be refinished and finally asking Ray Brazille (who I met in 1992) who concurred.
Collecting S&W is a learning experience. This forum is outstanding as it is a "collective" learning experience.
A new collector here, in 2018 on this forum,( if he or she is astute and studies well ) can learn more HERE in a few months than it took me over 40 years to learn.