The A2 was in production at the cut-off date in 1986, correct?

But that would be different than one made in 1990 as an A3?

Can someone explain the specific differences between the various receiver generations?

Or point to an m16 receiver guide that shows the differences

thanks

tagging for more info as well

The M16A2 was in production right before the 86 cutoff date.

There are 5 general M16 lower receiver profiles I am aware of.

Slabside Original receiver type with no fence along the magwell button.  i.e. Colt Model 601




Partial Fence  Next generation type with fence along the top edge of receiver.





M16 and A1  Full Fence


View of left side of an M16A1 receiver showing non reinforced ears and standard buffer/receiver extension ring.


M16A2  Full Fence and reinforced front takedown ears and buffer ring.  You can see how the front ears start to blend down into the receiver and the buffer ring swells a bit by the rear takedown pin and gains a second "ring" of material around the circumference.



Current Variant M4 Carbine/A4 The most up to date receivers feature a full fence and even more reinforcement around front takedown ears and buffer ring vs. the A2.  There is now a ever greater swell at the rear takedown ping necessitating what looks like a notch to the rear takedown pin and the front ears come down almost a 1/3 of the way down the front of the magwell.



I am sure there are probably even some more nuances between these high level variants and folks more knowledgeable than me can fill in any gaps.

In regards to Transferable Cots, the cutoff was officially at the A2 receiver mark.  However in the past couple of years we have seen transferable A2s come onto the market with obviously modern A3 receiver forgings.  It would appear that somebody connected at Colt got some older A2s factory replaced with new guns using the old serial numbers/paperwork....which in my estimation puts those guns in a legal gray area (just like the Oly replacement receivers)

See example A2 with modern A3/M4 forging.



Hope this helps.

Perfect, exactly the information I was looking for

Thanks very much

thanks for the info jbntex and tony

very helpful

I would like to know about the A3 reinforcements on the A2 and before receivers.

Now THAT is interesting!