Colt AR15A2 Lowers - what is different about them

[Marine24]

Looking to put together a Colt AR15A2 rifle. I have a complete upper I'm trading for but not entirely sure what is unique about the Colt AR15A2 lower. I believe the rifle stock and pistol grip is different from the SP1 models but not entirely sure how.

Goal is to build a 1980s representative model of the M16A2 but not planning on getting too anal about it unless the differences are significant.

[USMC88-93]

Commercial Colt, you will need to make sure of the pin sizes in the lower both the take down pins and the trigger pins are of different sizes based on when it was manufactured and/or commercial vs govt sourced. Aside from that some have a tool steel sear block, some have the rear area of the lower machined to not allow use of a sear....etc....

Realistically the only concern you have is making sure both your upper and the lower you utilize have the same take down pin hole size and location. Some Colt have non captive takedown pins as well.

If the upper you have is small pin and the lower large pin there is an adapter that can be used to mate the pair as well.

[mutt]

Looking to put together a Colt AR15A2 rifle. I have a complete upper I'm trading for but not entirely sure what is unique about the Colt AR15A2 lower. I believe the rifle stock and pistol grip is different from the SP1 models but not entirely sure how.

Goal is to build a 1980s representative model of the M16A2 but not planning on getting too anal about it unless the differences are significant.

Colt lowers marked AR15 A2 are really just SP1 lowers with A2 furniture and a different rollmark. They'll have the large front take down hole and are slab sides (no mag button fence). They will not be correct for a M16A2 clone and most likely wont work with your upper (without an adapter) if you have a real M16A2 upper or later Colt A2 style upper.

I wound up using a Colt Match Target HBAR rifle as the basis for my A2 clone since everything was mostly correct except for the barrel. I swapped out the barrel with a Colt Sporter II barrel assembly and got as close as possible to a M16A2 Colt clone - proper color, proper barrel profile and unmolested bayonet lug. Downside to my lower is it uses the large FCG pins and has a commercial rollmark. But I figured it was a good trade off overall.

[Circuits]

So what's most important to you? Being period correct for what Colt was selling at the time, or getting as close to a semi-auto M16A2 as you can? As has been mentioned, the product sold by Colt as the AR15-A2 ("Sporter II") was very different from the product they were supplying to the military as the M16-A2, and different from what is now known and accepted as a "semi-auto M16 variant".

You can always buy an actual 1980s-era M16A2 if you've got $35k-$40k laid back, and that will tend to be absolutely period-correct.

[Marine24]

Forgot about the pin differences and good point on the mag button fence. The part number of the lower is a R6900DC, which appears to be a Colt Sporter complete upper kit and was manufactured prior to 1994. It has Colt 223 on the left side of the receiver and should have the 0.25" front pivot hole based on what I'm reading.

May not be exactly correct, but my goal is representative and will have to live with the rollmarks. This is the same challenge I'm having with my M14 clone but my Winchester is pretty close san the selector switch.

Sounds like the slab side lower would be a good place to start.

[Marine24]

Pics of the upper








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[mutt]

If your upper has a .25 front pivot hole then you need one of the later colt A2 lowers. Look for a Match target or Colt AR15 A2 'Govt Carbine' lower from the 90's. They'll have the proper A2 fence, proper color anodizing and proper pivot pin hole size. However they will have the larger FCG pins but that isn't a big deal. Also look for one that doesn't have a sear block. Sear blocks look horrible and some can interfere with M16 profile carriers. Those lowers should also be cheaper than the less correct sporter II lowers. Some sporter II lowers are considered pre-ban in certain communist states so they command a price premium since rifles built off those can have "evil features".

You could also just go nodak spud if you don't care if the lower isn't a colt. It would save you some money and your lower would be dimensionally correct.

[Marine24]

Mutt: Thanks. This one is more of a wall hanger/occasional shooter so being a Colt is of greater importance.

Know what you mean about the pre-ban lowers and thankful I already have an A1 clone.