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Explanation of the AR types?

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Explanation of the AR types?

#1 Post by S.B. » Fri Aug 11, 2017 5:36 pm

By that I mean differences between -1s, -2s, -3s -4s? Pictures of each would help, please?
Steve

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Re: Explanation of the AR types?

#2 Post by RWS » Sat Aug 12, 2017 8:56 am

Sorry, Steve, I don't have pictures of all the variants. I'd have to pull them off the internet and it's likely that some, or all, of the pictures would be someone's personal property. The AR-15.com forum has lots of pictures though and is a good site to learn from. Many members are ex-military.

I will say that it can be very interesting to learn about all the different models. There are so many little engineering changes made that a complete listing of differences would be absurdly complicated. I will try to list the main visual differences. That may help somewhat.

I'll start with the M16 as it was the first official U.S. rifle. Prior to the M16 there were three different trial models (the models 601, 602, & 604) that were being used on an experimental basis by U.S. advisors in Vietnam and by a few special forces units.

Invitations to provide corrections are solicited if I missed something, especially on the A4 models as those are the ones I know the least about.

M16
-Semi & Full Auto fire modes
-Triangular handguards, no finger grooves on the grip, and short solid butt w/moveable rear sling swivel and no butt trap storage compartment.
-Rear sight adjustment requires bullet tip to adjust.
-Front sight is a round tapered post w/5 detents per 360 degree rotation.
-3-prong flash suppressor
-No forward assist on the upper receiver. Also called "slickside".
-Barrel twist is 1-in-12 (very early models were 1-in14) and the barrel profile is "skinny" from muzzle to receiver.

M16A1
-Semi & Full Auto fire modes
-Triangular handguards, no finger grooves on the grip, and short butt w/fixed rear sling swivel and butt trap storage compartment for cleaning kit introduced.
-Rear sight adjustment requires bullet tip to adjust.
-Front sight is a round tapered post w/5 detents per 360 degree rotation.
-Birdcage flash suppressor with open bottom (although the 3-prong fp was still used on the early versions).
-Forward assist with teardrop plunger.
-Barrel twist is 1-in-12 and the barrel profile is "skinny" from muzzle to receiver.

M16A2
-Semi & 3-round burst fire modes. (Canadian models retained full-auto capability instead of 3-rd burst).
-Lower receiver reinforced with extra material around the takedown push-pins.
-Round handguards, finger groove on the grip, and long butt w/fixed rear sling swivel and butt trap storage compartment for cleaning kit.
-High profile A2 rear sight with knobs for windage & elevation.
-Front sight is a square tapered post w/4 detents per 360 degree rotation.
-Birdcage flash suppressor with closed bottom.
-Forward assist with round plunger. Most with shell deflectors to accommodate left-hand shooters.
-Barrel twist is 1-in-7 to accommodate 62 grain bullets and the barrel profile is "skinny" from upper receiver to the front sight post and heavy from the front sight post to muzzle.

M16A3
-Semi & Full Auto fire modes as specified for U.S. Navy contract. Otherwise, same as A2 above.

M16A4
-Semi & 3-round burst fire modes.
-Flattop upper receiver with option for detachable carry handle or scope mounts.
-Modular rail system on handguards for most A4 models
-M4-style barrel relief cuts for improved feeding on later A4 models.

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Re: Explanation of the AR types?

#3 Post by S.B. » Sat Aug 12, 2017 6:35 pm

Thanks Bob, I couldn't have thought I may be missing something but, guess my guess was right after all. Kept thinking I missed something in all the engineering changes.
Steve

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