What is the diff between an "old" and a "new" AR-15?

[Purplehood]

Compared to many of the gun-enthusiasts on this website, I am just a novice and know pretty much only what I see in my monthly issue of American Rifleman and my own limited civilian and military experience about weapons in general.

If I recall correctly, back when I was a kid and my Dad was using the original M-16 (not M-16A1 or later), the civilian version was called an Armalite or AR-15.

Now I have what is called an AR-15, but it is a carbon-copy of the M-4 that I carried in Afghanistan.

Can anyone enlighten me on what it is that I am obviously overlooking when it comes to what the difference is regarding civilian versions of the venerable M-16 line?

[WEC]

AFAIK, when Stoner invented the rifle, he dubbed it the AR-15. The "M" designation was when the military adopted as standard issue. The biggest difference, of course, between the military version and its civilian counterpart (or vice-versa, as it were) is the select fire ability.

[Purplehood]

What I am more specifically asking, is that an AR-15 of the 70's is obviously different than the latest version. Yet it appears they are all referred to as AR-15s. What am I missing here?

[kd5zex]

The manufacturers began to make uppers with 16" barrels, a rail instead of the carry handle / rear sight and offer collapsible stocks, after the "assault weapons" ban expired I believe, to make a "M4gery" which resembles the M4 carbine currently issued to the military.

Here is a link to some of the various configurations of AR-15s you can get.

http://www.del-ton.com/AR_15_Rifle_Kits_s/1.htm

All evil black rifles chambered in 5.56 /.223 are traditionally called AR-15s regardless of barrel length or configuration.

[Cutter]

What I am more specifically asking, is that an AR-15 of the 70's is obviously different than the latest version. Yet it appears they are all referred to as AR-15s. What am I missing here?

Well, the "standard" AR-15 black rifle of the 70's was a fixed stock, full length barrel. These days you usually find the AR-15 in a collapsible stock/Carbine set up. Also, the carry handle is often omitted on many models. There are many variants of the AR-15 platform.

-CT

[nitrogen]

This might answer your question, in regards to the various revisions to the "M16" design:

M16A1: Addition of the forward assist
A2: New rifling, thicker barrel, improved front and rear sight, shell deflector
A3: full auto variant
A4: Flat top

More info on the variants is below:
http://en.wikipedia.org/wiki/M16_rifle#M16" onclick="window.open(this.href);return false;

[WEC]

What I am more specifically asking, is that an AR-15 of the 70's is obviously different than the latest version. Yet it appears they are all referred to as AR-15s. What am I missing here?

Yeah, I kinda figured that was what you were asking, but then I had to hurry off to work, heh.

+1 on Nitrogen's post.

[Purplehood]

I am pretty familiar with M-16s and their variants as I have been exposed to them for my entire adult life. The confusion lies with the AR-15s and their variants.

If I am understanding the posts thus far, the term "AR-15" is almost a generic term now for a large family of M-16/M-4 civilian variants. In other words, my AR-15 may be entirely different from someone elses.

I think I have beat this topic to death now.

[nitrogen]

Purplehood: pretty much.

The AR-15 was Armalite's name for what became the M-16, and was their trademark name for it.
So, you could say that the M-16 was an AR-15 before it was an M-16

These days, AR-15 usually refers to a semi-auto only version of the weapon, while select fire versions are usually called M-16's or M-4s. You could call all 3 "AR-15"'s ad be correct, but I think those are the terms that most people use and follow, right or wrong.