After getting a beautiful M1D with all accessories from the CMP last year, I went in search of information on the M84. Not much out there! A friend loaned me his 1947 copy of War Department Technical Manual TM9-1275 Ordnance Maintenance, U.S. Rifles, Cal. .30, M1, M1C and M1D (Sniper's). This lists specs on the M81 and M82 scopes as follows:
Both were Lyman Alaskan scopes produced for the military. The M81 had a cross-wire reticle and the M82 a tapered post, otherwise they were identical.The reticle was internally adjustable for windage and elevation in one minute of angle clicks. Numerical graduation marks had a value of two m.o.a.
The M84 scope replaced the M81 and M82 and was standard issue in April 1945. Peter Senich provided the most detailed information on these scopes that I have found in his book LIMITED WAR SNIPING, Paladin Press, 1977. I found this book at the library while researching info. on the M1D and M84. Chapter 4, Semi-Automatic Sniping System, The M1 Garand, goes into considerable detail on the history of the M1C, M1D and their scope and mount development programs. Page 63 opens the history on the M84 in early 1945. As a 2.2 X conventional design (T134) very similar to the M82, it was to compete in field tests against 3 X and 4.5 X designs in June of '45. For unknown reasons those scopes were rejected and the T134 adopted in April '45 as the M84. It has a universal focus, field of view is 27 feet at 100 yd, diameter is .870 in., length with rubber eye-piece and sunshade extended is 13.2 in., the reticle is a post with horizontal cross-wire, eye relief is 5 in. and it was sealed with rubber gaskets to keep out moisture. In my shooting with it, the top of the post appears to subtend 3 m.o.a., or 3 in. at 100 yd, 6 in. at 200 yd. etc. The elevation dial has 32 threads per inch which provides 40 m.o.a. of vertical movement of the post for one complete revolution of the drum. The finger adjustable knob gives 1 m.o.a. for each click, which are usually felt rather than heard. The elevation scale starts at zero yards and elevates to 900 yards with line marks every 50 yd. and numbers at each hundred yard increment. The windage knob has 20 m.o.a. adjustment both left and right of zero. It has a total windage range of 100 m.o.a. to allow for any mount misalignment. Like the elevation knob, each click moves the post 1 m.o.a.
Since the M84 was to replace those M81/82 scopes coming out of service, only a small number had been produced by the end of WW2. Certainly, none saw combat. The M84 was standard for the M1C, M1D and Springfield M1903-A4, but was not available in quantity until the Korean War. Libby-Owens-Ford was the military contractor. The M1D/M84 combination was a sniper rifle that could be assembled at the division armorer level as no drilling and tapping of the reciever was required as with the M1C. As a result, many more M1D's were prepared and distributed, seeing service into the late 70's.
An additional source of information on the M1D/M84 is the book, THE LONG RANGE WAR: SNIPING IN VIETNAM by Peter Senich, 1994. In chapter 1 he goes into some detail on the build up of U.S. military activity in the 60's and their reliance on the M1D. Very detailed information with excellent black and white photo's showing details of the various rifle/scope combinations in development are included.. As to the number of M84 scopes produced, the only hint I could locate was in a photo credit Senich gives on page 19, "....with a total of well over 40,000 M84 telescopic sights manufactured before production finally ended, and with the U.S. policy of "surplus disposal" such as it is, this 2.2 power scope will undoubtedly remain in service someplace on this globe for years to come."
I'm just grateful that the CMP made these M1D Garands available to good citizens and that I was fortunate enough to draw one in the last lottery. And what a fine specimen it is. Original Springfield in the 3022xxx serial range with a 1952 SA barrel with a fresh crown, milled SA trigger guard with all matching parts, new M84 in the original sealed packaging, clean walnut stock with no dents or dings and all the proper stamps, uniform grey parkerizing and all the accessories! HOT Dang! I just couldn't wait to get it all put together, cleaned, lubed and out to the range for a test drive, (which ought to drive the collectors/profiteers crazy). As an ex-SWAT team counter-sniper I have a real appreciation for the origins of our current equipment. The M1D/M84 was a real evolutionary step that led us to the more accurate systems that we benefit from today. Of course it doesn't deliver the pin point precision that a tuned Rem. 700 or Stoner SR-25 will, and the lateral zero shift at different ranges must be accepted, but I wouldn't volunteer to thumb my nose at a competent marksman within 600 yards. My rifle groups into 2 m.o.a., or less at 200 yards and the zero is relatively repeatable if the same hand only torque and positioning is applied to the mount. Calibration of elevation adjustments coincide very well out to 600 yards with the M 72, 174 grain fmjbt match ammo or equivilent reloads using the Sierra 168 grain Matchking. As Senich points out, the interior black coating used to retard light scatter in the M84 has a tendancy to flake and adhere to the interior lens surfaces. So what, just ignore it like a couple of generations of soldiers have.
In my area we put on a "Vintage Sniper's Rifle" match once each summer. All prone, 20 rounds at 300, 500 and 600 yards. Any nations "as issued" Korean War or earlier sniper rifle qualifies. Snugging the M1D into my shoulder with a tight leather sling, checking the post for vertical, the wind direction and velocity, and the mirage boil, I can smell the leather cheek piece as breathing is checked and slack taken from the trigger. Concentration of focus spirals through the M84 and I'm transported to other times and places when men at arms gambled far higher stakes. For some reason, this keen appreciation of history, and freedom, just doesn't occur with the SR-25 from the 600 yard line. Hope this assists you in your search for more information on the M84.
To get additional elevation and widage corrections the caps must be removed by removing both the small inner and larger outer locking nuts retaining the adjustment knobs. The inner nut is difficult to remove without a special slotted tool. The inner nut prevents the larger nut from being removed completely and serves as a stop. After carefully removing the inner nut, the larger outer nut can be loosened and removed.
After the knob(s) are removed, further adjustments can be made by turning the internal adjustment disc on either the windage or elevation or both. This will give you a macro adjustment to get you close. The cap is then reinstalled along with both nuts. Do not tighten the larger nut as micro adjustments will still be needed. Care must be taken to avoid losing anoy of the small nuts.
You should probably do this at the range.
The mount base is part of the "D" barrel assembly, and was never issued as a separate part.
There are some Chinese made blocks sold by some companies, but they are of poor quality, and the threads can be a big problem. Keep in mind, after paying all that money to convert your barrel, if the threads go bad, you've lost that barrel for the intended purpose, and, yu've ruined your original barrel.
Besides, a Chinese block will render the rifle uncollectible, and the only scope you can use is a rather poor M84 that costs more than a very good scope made today.
Best advice: If you want to scope the rifle and not alter the receiver, get the scope mount with included 1" rings (or the Weaver Rail version) from Fulton Armory for around a hundred bucks, and get a decent 1" scope.