AR designations

[reloadem]

I am new to AR's, and have been looking for descriptions to the terminology, can't find it yet.

What is an A1, A2, A3, A4?

[SSGN_Doc]

A1- refers to a fixed carry handle type that has a windage adjustable rear sight with no elevation adjustment. The A1 also features a forward assist. No brass deflector. Barrel rifling had a 1:12 inch twist.
There is a C7 upper that is eseentialy the same with an added brass deflector and is in use by the Canadian armed forces.

A2- Incorporated a new rear sight that was elevation adjustable, as well as windage adjustable. They also added a brass deflector. The forward assist knob was changed from a tear drop shape to a round shape. New rifling twist rate was changed to a 1:7 to accomodate heavier/longer projectiles found in the 62 grain rounds and to stabilize the new tracer ammunition to go along with it.

A3 is pretty much an A2 with a removeable carry handle.

M4 was a change to a carbine with removeable carry handle, feed ramps cut into the reciever for more reliable full auto/ burst feeding. Barrel length was reduced to 14.5" with cuts to accomodate the mounting of a grenade launcher.

There are other finer points, and I may be a bit sketchy on A3, but that's the basics. Others will be along to give more detail, and correct my mistakes.:D

[flyboy1788]

A1- refers to a fixed carry handle type that has a windage adjustable rear sight with no elevation adjustment. The A1 also features a forward assist. No brass deflector. Barrel rifling had a 1:12 inch twist.
There is a C7 upper that is eseentialy the same with an added brass deflector and is in use by the Canadian armed forces.

A2- Incorporated a new rear sight that was elevation adjustable, as well as windage adjustable. They also added a brass deflector. The forward assist knob was changed from a tear drop shape to a round shape. New rifling twist rate was changed to a 1:7 to accomodate heavier/longer projectiles found in the 62 grain rounds and to stabilize the new tracer ammunition to go along with it.

A3 is pretty much an A2 with a removeable carry handle.

M4 was a change to a carbine with removeable carry handle, feed ramps cut into the reciever for more reliable full auto/ burst feeding. Barrel length was reduced to 14.5" with cuts to accomodate the mounting of a grenade launcher.

There are other finer points, and I may be a bit sketchy on A3, but that's the basics. Others will be along to give more detail, and correct my mistakes.:D

I talked to a marine who said they used a4s. whats the diff between this and an a3

[Failure2Stop]

The civilian side designations of A3 pretty much mean that it has a flat-top upper.

On the military side it means that it has an AUTO setting instead of a BURST setting, and may or may not have a flat-top upper. Now, it might not have been the intention of the manufacturer for the A3 to have an A2 upper, but I have seen A3s with both A2 and flat-top uppers.

The A4 is simply an A2 with a flat-top upper- whether or not the weapon features a rail system is up to the end user, though the USMC ones have a KAC rail.

ETA- FWIW a search of "m16a4" yielded many useful results, along with this one- click me (https://www.m4carbine.net/showthread.php?t=15945&highlight=m16a4).

[reloadem]

Thanks, that has been a lot of help.

[DarkX]

To add to the above description of an A1

Early A1 series had no forward assist or deflector nor did they have a fence/ridge around the mag release button...hence the nicks of slickside or slabside. When forward assist did appear it was with a teardrop rather than a button. They also have triangular handguards and smaller profile barrels.

Additionally, early flash hiders were prong, later converted to the birdcage similar as is seen on current series with the exception of the fact that the bottom of the FH was slotted....A2 and later have a solid bottom FH.

[K.L. Davis]

The technical specifications for an A3 are a rifle with an fixed (A2) carry handle and the full-auto FCG, I do not know of an approved configuration that changes that... the A4 has three different configurations.

As FTS stated though, that does not mean that someone, somewhere has not swapped an A4 upper on to an A3 lower... approved configuration changes be damned :cool:

I don't know about an A1 with no FA? With all of the hoopla surrounding the E1 and the FA, it seems odd that an A1 sans FA would make it into the wild... same with the mag release fence and stuff -- it was a bitch opening C-Rats without a "Duckbill" though (or so I've been told, of course I am not that old :( ).

[BretShooter]

To add to the above description of an A1

Early A1 series had no forward assist or deflector nor did they have a fence/ridge around the mag release button...hence the nicks of slickside or slabside. When forward assist did appear it was with a teardrop rather than a button. They also have triangular handguards and smaller profile barrels.

Additionally, early flash hiders were prong, later converted to the birdcage similar as is seen on current series with the exception of the fact that the bottom of the FH was slotted....A2 and later have a solid bottom FH.

You described the Pre-A1's (merely an M16). They also didn't have a chrome barrel until M16E1, which was standardized as an A1, along with all of the previous features.

[Ross]

The military uses different designations than many civillian companies. So there's alot of confusion because the civillian designations were driven by marketing/sales and the military's were driven by the order that the variation was adopted.

The Base M16 has fixed sights and no forward assist. It was used by the USAF mostly.

The A1 had fixed sights and forward assist. It was used by the Army and Marines mostly.

The A2 had adjustable sights, forward assist, and had "burst" in place of full-auto. It replaced the A1 mostly. There was to be a USAF version without Forward assist, but having the rest of the A2 features, but it didn't seem to materialize for whatever reason (I'm guessing funding).

The A3 is an A2 with full-auto instead of burst. The difference in the designation is not the type of upper, but the change in burst to full-auto. So you can see different uppers on an A3. It was originally developed for Army SF, but they went to the M4 and the Navy has been the big user of the A3.

The A4 is the current USMC rifle and is basically an A2 with a flat-top and rails.

Like all things in the real-life military, there are plenty of exceptions, odd-ball assemblies, and variations of the above.

Some civillian compaines use "A3" for a flat-top because they don't deal with the full-auto feature much and it was the logical progression of the rifle. But the military used a different logic.

The big thing to remember is that the military and civillan number schemes may or may not be the same for any given item, and there are always exceptions.