Carry Handle!

Ravenclaw Eric wants to know about carry-handle uppers.

I sometimes forget that not everyone is intimately familiar with ARFCOM jargon.

There are five basic types of AR upper receiver.

Slick side.  This is the earliest style.  It's found on the R601, R602 and R604 rifles.  The R604 is also known as M16.  There are sub-variations too, the one pictured is an R604 upper.  It's called a slick-side because there's no forward assist.

A1.  This is the second style.  It was introduced with the R603 rifle issued as the XM16E1 and M16A1.  It's the same as the slick-side except they added a forward assist (at the Army's insistence). It's called the A1 because that's the gun it was introduced with.  Interestingly, almost any retro AR part is called an 'A1' part even if those same parts are present on an M16 A-nothing.

C7.  When we were getting ready to issue the M16A2, the Canadians decided they liked the idea, but didn't want the complicated rear sight.  So they issued an M16A1 upper with the addition of the "Brutton Bump" just behind the ejection port; this is a brass deflector that makes the gun more lefty friendly.  It's called the C7 because that's the Canadian name for their M16 variation.  Notice also that the anodizing changes from gray to black.  Irritatingly, this style upper is misleadingly sold as an A1 from many vendors.  If it matters to you, look for the bump!

A2.  Introduced with the M16A2 (can you see where the common names are coming from yet?).  The Marines shoot at known-distance ranges so they demanded and adjustable rear sight, here it is.  This also introduces the Brutton Bump to US rifles.  The M16A2 also introduced the three-round burst, an M16A3 is the same rifle with full-auto.  This gets confusing later.

Flat-Top.  The four previous uppers are also known as "carry-handle" uppers because of the carry handle built right in.  The flat-top upper replaces the handle with a section of Picatinny Rail.  It was introduced with the M4 carbine and is present on the M16A4.  Remember when I mentioned the M16A3 thing would get confusing?  Well, the flat-top is also known to some as an A3 upper.  When it hit the civilian market the Navy had not yet created the M16A3 so it was assumed that the next M16 variation was going to be a flat-top.  The rear sight shown here is not part of the upper, it can be removed (if I want to lose my zero.)

Here's why the flat-top was adopted!  Scope mounts that attach to the carry-handle put the eye-line way too high.  It's hard to get a good cheek-weld.

Here's one example of why we didn't just carry on with the carry handles.  This is what's known as a gooseneck mount.  It puts a red-dot in a usable place, but it still gives a poor cheek-weld and to use the irons you have to unscrew either the mount or the optic.  If you detach the scope, the mount is still in the sight picture and can take some getting used to.

This just skims the surface; but I hope it's informative.