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National Match rear sight characteristics

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I would like to learn how to distinguish an original N.M. rear sight from a currently manufactured one. On original rears sights did specific manufacturers (sayTRW) so mark their sights or exibit any different characteristics, ie. course machining marks ? Proof marks? etc.
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The NM Base has 1/2 MOA adjustments in WINDAGE and and the windage knob has 1/2 MOA serrations to correctly mate with the NM base with 1/2 MOA's.
The older style NM base is a USGI (stamped NM) and a forged base and difficult to find as well as expensive. (Well more expensive than the NM2A…)
The newer style NM base is marked "NM2A" and is investment casted. Allot of the M1A gunsmiths out there are using the NM2A and it is a very fine base and you RARELY hear that someone has encountered a problem with them. I have one on my NM SA M1A for a year now with no problems. The NM aperture is what allows you to adjust the elevaton in 1/2 MOA increments. (outlined blow)

The following was taken from the FULTON ARMORY SITE http://www.fulton-armory.com/
A. The two aperture assemblies are identical except for the eyepieces which have different peep hole diameters. The aperture with the .0595 in. peep hole will be installed as standard with the .0520 diameter aperture available as an alternate.
The hooded eyepiece is designed to eliminate glare and reflections on the sight aperture, and to provide 1/2 minute changes in elevation. Each eyepiece is selectively fitted and matched with its individual aperture. You should not attempt to disassemble the aperture assembly or to change eyepieces on an aperture.
The peep hole is .002in. vertically eccentric with the other diameters of the eyepiece. Thus rotating the eyepiece 180 degrees clockwise or counter-clockwise raises and lowers the line of sight. Two spring-loaded balls in the eyepiece engage a vertical "v" notch in the face of the aperture to retain the eyepiece in each position. The position of the eyepiece is indicated by a notch at the rear face of the eyepiece.
Each click of the elevation knob gives a change of 1 minute. Rotating the eyepiece so that the indicator notch is at the top moves the point of impact of the bullet up 1/2 minute. With the indicator notch at the bottom, the point of impact of the bullet will be moved down 1/2 minute. In operation you would use the elevation knob to get just above or just below your desired point of impact, and then rotate the eyepiece up to get an additional 1/2 minute of elevation or down to lose a 1/2 minute.
B. The National Match sight base marked "NM/2A" is undercut to accept the hooded eyepiece. The 64 pitch thread of this sight base and of the National Match windage knob produce a 1/2 minute change in windage for each click of the knob. Thus the National Match Rear Sight is capable of 1/2 minute sight changes for both windage and elevation.
C. The National Match front sight has a blade width of .065 -.005, and is identified by the letters "NM" and the numbers "062" on its right side. The width of the sight blade of the standard M1 or M14 rifle is .084 -.010.


The base and the aperture HAVE to be properly fitted to your rifle if you want all the components to function properly.

I hope that helps... :)

Regards,
 

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NM Sights

Besides what has previously been stated, it can be very difficult to distinguish between original and aftermarket NM sight parts. Milled parts will not have casting marks, but some late GI parts were cast. The aperture slide on many commercial reproductions will exhibit thicker dimensions and often will bind when assembled to the rifle. Note that one GI contractor marked it's NM base with white ink rather than stamping the numbers in and I have seen some that appear to have been etched. There have been several makers of windage knobs since the original NM parts were made. My observation is that they are all identical and work well.
 

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Discussion Starter · #4 ·
N.M.rear sight

Thanks guys,so then as far as you know there is no way to tell an individual maker of the rear sight say TRW as opposed to SA ? I am 98% complete on an ALL TRW M1A (excluding receiver) and dont want to get crazy looking for a TRW marked rear sight ,if they do not exist. To the best of your knowledge.
 

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Discussion Starter · #5 ·
national match rear sight

On original rear sights when you say "stamped" were they actually stamped, where metal is displaced around each letter? Or were the N.M markings as on the barrels , that appear to be pantographed or roll stamped? Lastly, are the currently made rears marked N.M. and how?
 

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Discussion Starter · #8 ·
N.M. rear sight

Any way to look into whether N.M. rear sights were one of the eleven parts? Better yet where do i look to find out what all eleven parts were? I am trying to build a complete TRW national match rifle.
 

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Discussion Starter · #10 ·
N.M. rear sights

Thanks Fubar, i did check "Differents" on line book. It did indicate that TRW made bases for std. rear sights. I would assume that the only difference between a std or N.M. rear sight base would be the letters N.M. stamped into the base.
 

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NM/2A

On the right of the National Match sight base will be NM/2A and you will have to FIT the National Match hooded aperture to the sight base. It won't slide in the channel, it will be to wide. And you will need a National Match Windage Knob. It will be marked with an NM also.
 

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Your original question, how to tell the difference from 1960's production vs todays. One way is to know the evolution of the parts. The first base was NM marked because there was no hooded aperture. That base was cut down at the depots when the hooded aperture came out and it was marked NM2. When the base was manufactured with the hood clearance cut, it was marked NM2A.

The windage knobs can be distinguished by knowing which manufacturers were around years ago and which are being made today.

Apertures are a tough one. Except for a couple of makers, today's apertures look like the old ones.

As far as the poster that said "I would assume that the only difference between a std or N.M. rear sight base would be the letters N.M. stamped into the base.", the difference is in the thread pitch. The two bases, although they look the same, are very different.
 

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aperture

woodpuppy said:
so if one wishes to fit a hooded aperture to a new USGI non-NM base, it will not go all the way down?
No, it will go all the way down, it's just that when it is all the way down in the base, in actuality because the base is not "undercut" to accept the hood, you will already have a few clicks of elevation attained with it down as far as it goes.
 

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Discussion Starter · #16 ·
N.M. rear sights

Bill R. , you mention that by knowing which manufacturers were around years ago, that the rear sight manufacturers can be destinguished, by the windage knobs. Are you saying that the windage knobs were marked as to the manufacturer? ie. TRW or SA etc.
 
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