Carry handle question

[agr1279]

Your rear sight it fine. Shoot it and you will see it only affects the OCD.

I spoke to Frank at CLE at his shop in late 2001 about pinning the rear sight. He said it was not necessary. He showed me on my upper the amount of deviation in the spring holding the rear sight in position. He put a gauge on it and it returned to zero every time.

He did say if I wanted my sights to send the to White Oak (John Hollenger). He did not provide the service.

There was a shooter at Perry whose rear sight was pinned which took a tumble in the pits. It fell on the rear sight bending the pins.

I hope this helps.

Dan


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[lysander]

Since we're talking here about the line of sight passing through the center of the circle/oval, I'd like to ask a peripheral question about the line of sight in relation to a mil-spec carry handle: What exactly is the vertical distance between the center of the long-distance aperture and the bore axis at mechanical zero? I've come across "about 2.5 inches" and "about 2.6 inches." Shouldn't there be a little more precision here?

With the M16A2 and its style of sight the height of the aperture is quite variable.

M16/M16A1
Rear Sight (short) = 2.567"
Rear Sight (long) = 2.576"
Front Sight (base flush) = 2.553"

M16A2 (rear sight base fully down)
Rear Sight (short) = 2.565"
Rear Sight (long) = 2.580"
Front Sight (base flush) = 2.598"

M4 Detachable Carry Handle (rear sight base fully down)
Rear Sight (short) = 2.608"
Rear Sight (long) = 2.623"
Front Sight (base flush) = 2.630"

(All +/- 0.015" to 0.020" for tolerances)

[Rifleman_04]

When the M16 Product Improvement Program of the early 1980's was cranking up The Army pretty much gave the Marine Corps a free hand in most of the details. The Marine Corps pretty much handed it to the competition gurus at Quantico. There are a few things which ended up in the final M-16 A2 configuration that can lead to some "head scratching" when viewed through a gun-fighters eye. When viewed through the eye of a service rifle competition shooter things make slightly more sense. But like the man said ".... We ain't going to Wyoming to shoot canteens boy....”

False. The project was handed over to a Marine infantry officer with combat experience in Vietnam. The rear sight was taken from a Colt LMG prototype with zero input from competition shooters.

[lysander]

False. The project was handed over to a Marine infantry officer with combat experience in Vietnam. The rear sight was taken from a Colt LMG prototype with zero input from competition shooters.

The basics go way, way back . . .



I would say the rear sights of the Colt LMG and the M16A2 are concurrent designs. The M16A1E1 was being designed and built around 1979-80, the patent for the LMG, showing the new rear sight was filed in 1981.

[Rifleman_04]

Always appreciate your contributions, Lysander.

I was referring to David Lutz saying in an interview he copied the rear sight almost directly from the LMG prototype at the Colt factory sometime between that 80-83 time frame.

Edit to add: According to ColdBlue(Col. Lutz) on arfcom the “A2” rear sight was added to the prototype E1 receivers at Colt in 1982.

[Gulfton]

With the M16A2 and its style of sight the height of the aperture is quite variable.

M16/M16A1
Rear Sight (short) = 2.567"
Rear Sight (long) = 2.576"
Front Sight (base flush) = 2.553"

M16A2 (rear sight base fully down)
Rear Sight (short) = 2.565"
Rear Sight (long) = 2.580"
Front Sight (base flush) = 2.598"

M4 Detachable Carry Handle (rear sight base fully down)
Rear Sight (short) = 2.608"
Rear Sight (long) = 2.623"
Front Sight (base flush) = 2.630"

(All +/- 0.015" to 0.020" for tolerances)

Thank you so much. That is exactly what I was looking for.

[lysander]

Always appreciate your contributions, Lysander.

I was referring to David Lutz saying in an interview he copied the rear sight almost directly from the LMG prototype at the Colt factory sometime between that 80-83 time frame.

Edit to add: According to ColdBlue(Col. Lutz) on arfcom the “A2” rear sight was added to the prototype E1 receivers at Colt in 1982.

"Final Report Technical Feasibility Test of M16A1E1 Rifle, period covered- December 1981 through November 1982" by M.K. Humphreville and G.B. Niewenhouse, APG, MD, Published Feb 1983.

"With the expected US approval of STANAG 4172, a strong consideration was given to changing the barrel twist on the M16A1 to a 1 in 7 configuration to accommodate the heavier SS109 type round. In the process of producing a barrel with different rifling, the opportunity to strengthen this new barrel to correct ä bending problem was also implemented. These two improvements, plus improved plastic handguards and buttstock, constitute the primary emphasis of this modification. The US Marine Corps fully supported the use of the heavy bullet. Accordingly, the Joint Services Small Arms Program (JSSAP) office at ARRADCOM procured modified M16A1 rifles (designated M16A1E1) that incorporated those potential improvements for evaluation.

"Prior to the start of testing three other components were added. These included a muzzle brake compensator (MBC), a burst control device (BCD) that limits automatic fire to 3-round bursts, and an adjustable rear sight (ARS) that allows adjustment out to 800 meters.

"These modified rifles (M16A1E1) and the standard rifle (M16A1) were tested at APG, MD starting in December 1981. Testing was completed in November 1982."

"1.2 DESCRIPTION OF MATERIEL

. . . "The standard rear sight, adjustable for windage only, is replaced on the improved rifles with a sight capable of windage and range adjustments, out to 800 meters. The windage is adjusted by a finger manipulatable knob as opposed to the detent locked, adjustable disk of the standard rifle that required a tool for detent release. With the short range requirements of the standard rifle, this arrangement was rugged and dependable but the proposed longer range requirement of the improved rifle calls for a faster sight adjustment.

"The front sight of the standard and improved rifles are similar in function but the improved post is square in cross section as opposed to round for the standard. It is proposed that this will give better post edge definition to the shooter's eye under a variety of lighting conditions."

The ten M16A1E1s delivered to Aberdeen Proving Grounds in November 1981 had an adjustable rear sight, shown below. The reasoning behind the adjustable rear sight was that the effective range of the new STANAG 4172 bullet was longer than the M193 and and adjustable rear sight was required to take full advantage of that extra 300 yards, as windage would be more important and the drop at 500-600 yards was more that just a flip-type "L" sight could handle.



There are a few differences between the M16A1E1 rear sight and the M16A2 rear sight. The windage knob and elevation index were made from plastic, but the biggest difference was the M16A1E1 rear sight had arear viewing hole in the handle so the elevation setting could be seen from the shooting position. There was a problem in that there was an index line on the side of the handle same as the M16A2 and a second set of elevation marking on top of the elevation index. So from the side you could see two elevation numbers that did not agree (see bottom picture).

[lysander]

Oh, and another thing -

Most of the M16A2 drawings are dated mid-1982, so the design was pretty much finalized by then.

[weme06]

Wow, can't believe how much information this thread produced. And it's free.

[lazar]

Completely normal, the rear sight has a spring and detent/ball that pushes it towards 11o'clock. As for having to adjust 9 clicks of windage, that's not too bad, as there are about 40 clicks of adjustment from center if you go right or left, so 80+ clicks.