hey guys...i am pretty new to the AR world and am getting more confused day by day...what are the differences between the Ax numbers (A1, A2, A3 etc..?)...small hole verse large hole?  what holes?  just difference between brands?

i know i have more questions, but that's all that come to mind right now...any help would be great!!!(i'm a pic guy too)

wauster

Here's some reading material for you:

Actually really damn good Wikipedia article on the M16

AR15 Ammo Oracle

General Information Thread

BiggerHammer's AR FAQ

Grab a cold one and read away.  I'll edit this post in a few minutes with some specific details for you.

EDIT:
Ok, now its time for some Google-fu to try and answer your questions.  Better grab another cold one, I did.

Here's an M16.  Not A1, A2, blah blah, just original M16, circa 1965.


Note the extremely thin barrel, "3-prong" flash hider, and "slab side" upper reciever with no forward assist or brass deflector.  This was the variant initially shipped to Vietnam and advertised as a "self cleaning rifle".  The self cleaning rifle promptly met up with the red clay of 'Nam and got itself an awful reputation in a hurry.

Therefore, changes were hurriedly made to create the M16A1, the most prolific variant of the Vietnam era and the 1970s in general.


Note that the barrel is the same but the flash hider has changed to the "birdcage" style.  I've heard that this is because GIs were using the original flash hider as a pry bar, but I don't really know if that is true.  A "forward assist" mechanism has been added to the side of the upper receiver.  The idea is that if the gun fails to go into battery you can smack the button on the back of the receiver and simply shove the round into the chamber manually.  In 2008, some 40 years later, the usefulness of this feature is still hotly debated and I'm pretty sure the majority of operators believe that if a round doesn't want to chamber properly by itself, forcing it into place is a great way to catastophically jam the firearm.

Anyway, the original M16 and A1 were issued with 20 round magazines.  The designer of the M16, Eugene Stoner, stated in an interview that he thought that 20 rounds of capacity was fine until our troops in Vietnam started fighting NVA soldiers equipped with AK47s which held 30 rounds.  Hurriedly a 30 round magazine was developed and issued.

Here's a closeup of an "A1" style receiver:


Note the rear sight, which requires two rounds of 5.56 ammunition to adjust, and the forward assist mechanism.  A brass deflector has been added behind the ejection port to allow left handed shooters to fire the gun without spent casings bashing them in the face.  Some early A1 receivers, such as the one in the photo above this one, have the forward assist but no brass deflector yet.

More in a few minutes...

In the early 1980s the A1 started to be gradually phased out in favor of the M16A2.  The A2 had a heavier, more accurate barrel, a slightly different flash hider, round handguards, and longer stock.  The ability to fire full auto was replaced with a complicated mechanism that fired bursts of 3 rounds each time the trigger was pulled.  This was to discourage abusing the firearm and wasting ammo by indiscriminately dumping entire magazines with a single trigger pull, as often seen in Vietnam, and forcing the soldier to slow down and pull the trigger multiple times before the magazine would empty.

I had a surprisingly difficult time finding a decent pic of an original configuration M16A2.


Here's a closeup of the A2 rear sight.


Note that the sight can be moved with bare fingers now.  The adjustment is also much finer than on the A1 and can be instantly adjusted in the field to adjust for various ranges.  

In the early 1990s the US government wanted to adopt a carbine version of the M16 to replace obselete submachineguns still in the inventory, such as the M3 "greasegun".  Special forces units had built or requisitioned customized "chopped" versions of the gun since the early days of Vietnam, but the Colt M4 was the first carbine version to be issued in very large numbers.

Colt's pictures suck, so here is a CMMG version of the basic M4A3:


The A2 sight and carry handle now completely detach from the upper receiver, which features a standardized 1913 Picatinny rail.  This allowed various optics and accessories to be attached to the rifle instead of basic iron sights.  This is the "A3" configuration receiver.



Before long, various companies were marketing rail systems which replaced the thick handguards entirely, allowing an unprecedented ability to hang specialized doodads off of the rifle.

To wit:


More later.  Time for lunch.

height=8

DUKE'S Info

Wow man.  I'm trying to take all this in and a lot of things are lining up for me know.  It really is starting to make sense.  I BOW TO DUKE *insert smiley that bows*

Quoted: Quoted: Here's an M16.  Not A1, A2, blah blah, just original M16, circa 1965. world.guns.ru/assault/m16.jpg Note the extremely thin barrel, "3-prong" flash hider, and "slab side" upper reciever with no forward assist or brass deflector.  This was the variant initially shipped to Vietnam and advertised as a "self cleaning rifle".  The self cleaning rifle promptly met up with the red clay of 'Nam and got itself an awful reputation in a hurry. Don't forget the nitwit .gov "engineers" who changed the ammo from Stoner's specification of using a fast burning ball powder to using a slower burning flake powder, which promtly caused many jams.  Eventually the ammo was changed back to using fast burning ball powder and miraculously, almost instantly, that set of problems went away. See how the .gov can take a well-functioning thing and muck it up in a hurry?

From a cleaner burning "STICK" powder to a Dirty as hell "BALL" powder!

and added the NEVER needed it Forward Assist and the Shoulda always had it Chrome lined chamber and Barrel! The Red clay had little if anything to do with it, but the Humidity and steel Cased ammo as well as Mr Red Rust had a LOT to do with it!

Quoted: Quoted: Quoted: Here's an M16.  Not A1, A2, blah blah, just original M16, circa 1965. world.guns.ru/assault/m16.jpg Note the extremely thin barrel, "3-prong" flash hider, and "slab side" upper reciever with no forward assist or brass deflector.  This was the variant initially shipped to Vietnam and advertised as a "self cleaning rifle".  The self cleaning rifle promptly met up with the red clay of 'Nam and got itself an awful reputation in a hurry. Don't forget the nitwit .gov "engineers" who changed the ammo from Stoner's specification of using a fast burning ball powder to using a slower burning flake powder, which promtly caused many jams.  Eventually the ammo was changed back to using fast burning ball powder and miraculously, almost instantly, that set of problems went away. See how the .gov can take a well-functioning thing and muck it up in a hurry? From a cleaner burning "STICK" powder to a Dirty as hell "BALL" powder! and added the NEVER needed it Forward Assist and the Shoulda always had it Chrome lined chamber and Barrel! The Red clay had little if anything to do with it, but the Humidity and steel Cased ammo as well as Mr Red Rust had a LOT to do with it!

We were using steel cased ammo, similar to wolf? I'm not calling you wrong, I just had no idea...

Quoted: Quoted: Quoted: Quoted: Here's an M16.  Not A1, A2, blah blah, just original M16, circa 1965. world.guns.ru/assault/m16.jpg Note the extremely thin barrel, "3-prong" flash hider, and "slab side" upper reciever with no forward assist or brass deflector.  This was the variant initially shipped to Vietnam and advertised as a "self cleaning rifle".  The self cleaning rifle promptly met up with the red clay of 'Nam and got itself an awful reputation in a hurry. Don't forget the nitwit .gov "engineers" who changed the ammo from Stoner's specification of using a fast burning ball powder to using a slower burning flake powder, which promtly caused many jams.  Eventually the ammo was changed back to using fast burning ball powder and miraculously, almost instantly, that set of problems went away. See how the .gov can take a well-functioning thing and muck it up in a hurry? From a cleaner burning "STICK" powder to a Dirty as hell "BALL" powder! and added the NEVER needed it Forward Assist and the Shoulda always had it Chrome lined chamber and Barrel! The Red clay had little if anything to do with it, but the Humidity and steel Cased ammo as well as Mr Red Rust had a LOT to do with it! We were using steel cased ammo, similar to wolf? I'm not calling you wrong, I just had no idea...

Read up on it, yes it was not wolf but was US made steel cased ammo, if you look at photos from the time you can see OD green belted ammo hanging from M-60s and so on. But even at that if it were brass case and there was some of that too the Moisture and corrosion would have been similar!

Back from lunch.  Don't know anything about us using steel cased ammo in 'Nam, I thought we used M193 ball which is brass cased.

/bows to AFSOC

So, we've gone from M16 to M4A3 so far.  Now it gets a bit tricky.  The "flat top" picatinny rail receiver is sometimes referred to as A3 and sometimes as A4, interchangeably.  From a civilian standpoint it really doesn't matter.  From a military standpoint the only A4 that I know of is the US Marine Corps M16A4, which was adopted as the Marines' general issue rifle just before Operation Iraqi Freedom in 2003.  This is basically a 20 inch barreled, full size M16 with burst fire and the flat top receiver, and usually a Knight's Armament rail system replacing the handguards.  The Marine Corps also fitted a large number of these rifles with the Trijicon ACOG (Advanced Combat Optical Gunsight).  In my not-so-humble opinion, the M16A4 with ACOG is probably the deadliest rifle ever generally issued to the ordinary riflemen of any military branch of any country, ever, in the history of the world.  

Here it is.  


Here is a bigger version which I just made my desktop wallpaper photo.
upload.wikimedia.org/wikipedia/commons/b/b4/USMC_M16A4_Rifle.JPG

In early April of 2004 the Marine Corps commenced Operation Vigilant Resolve in Fallujah, Iraq in response to the killings of four American civilian contractors there.  A cordon was formed around the city and some 70,000 civilians, around 1/3 of the city's population, were allowed to leave.  Humanitarian relief trucks were allowed into the city but were carefully screened after weapons were found in some of them.  Elements of the New Iraqi Army were supposed to support the Marines' entrance into the city, but the vast majority of them fled their staging areas and deserted, leaving behind their uniforms but taking their weapons with them.  

The Marine Corps was determined to pacify the city themselves although it was known that some 12-24 seperate groups of insurgent forces were barricading themselves and laying ambush in various areas of the city.  Casualty estimates for MOUT (military operations in urban terrain) conducted in the 1990s had led military leaders to believe that an invading force entering a city with defenders who had time to prepare would take up to 50% casualties in the subsequent house-to-house fighting.  Experience in the city of Hue in Vietnam, and more recently the Russian experience in the invasion of Grozny, Chechnya in 1999-200, had confirmed these numbers.  The Russians in particular had suffered greatly, with thousands of casualties inflicted even after shelling the city to bits.  They even launched five SS-21 ballistic missiles into the city center and it still didn't matter, the defenders badly mauled the Russian army and in particular the tank forces.  The Marines chose to go in largely without heavy armor support, which is of limited use in built up areas anyway.

But I digress.  The point is that the M16A4, combined with the level of training of the typical US Marine vs. the level of training of the typical indigenous fighter, resulted in only 27 US combat deaths, compared to hundreds of Iraqi fatalities (the exact number is in dispute and will never be known, but is likely somewhere between 600-1000 including civilian casualties).  An investigation was ordered by the NCIC over the large number of insurgent bodies found dead by headshot, and subsequent concerns that US troops might be executing captured insurgents.  The investigation found, however, that the preponderance of headshots was due to the extremely good marksmanship of the US Marine and his rifle, and this is how stories of confirmed headshots at extended ranges became known to the public.  Marines were simply firing at the part of the bad guy they could see, and scoring hits as the insurgents poked their heads up, at ranges up to and including 500 yards.

Anyway, you wanted technical info, not a history lesson.  My bad.

Lets see, you asked about small hole vs. large hole.  Colt is the only manufacturer to make "large hole" upper and lower receivers, which are not standard "military spec" size and are not supported by any other manufacturer.  Unlike standard size receivers, which use a standard pin, the Colt system requires a flat head screwdriver to separate the lower from the upper.  If you do want to put a "large hole" upper on a "milspec" lower, or vice versa, a clunky adapter kit is required.

All real men prefer small holes.  'Nuff said about THAT.

As far as what brands to go with, everyone is entitled to their own opinion.  Ask AR15 guys what is best and you'll get different answers all the time, that's why this website exists.  For me, I'm a "parts is parts" kind of guy, I believe that inanimate objects don't know what name is printed on the side of them.  Furthermore, there is such a blindingly diverse range of configurations for AR15, that it really becomes a question of what the shooter wants to do with the rifle.  There are ARs out there that cost thousands of dollars, which I have absolutely no use for whatsoever.  On the other hand there are certain items which I pretty much demand in an AR, such as a chrome lined barrel, and other people have no use for those features at all.  

Quoted: Quoted: Quoted: Quoted: Quoted: Here's an M16.  Not A1, A2, blah blah, just original M16, circa 1965. world.guns.ru/assault/m16.jpg Note the extremely thin barrel, "3-prong" flash hider, and "slab side" upper reciever with no forward assist or brass deflector.  This was the variant initially shipped to Vietnam and advertised as a "self cleaning rifle".  The self cleaning rifle promptly met up with the red clay of 'Nam and got itself an awful reputation in a hurry. Don't forget the nitwit .gov "engineers" who changed the ammo from Stoner's specification of using a fast burning ball powder to using a slower burning flake powder, which promtly caused many jams.  Eventually the ammo was changed back to using fast burning ball powder and miraculously, almost instantly, that set of problems went away. See how the .gov can take a well-functioning thing and muck it up in a hurry? From a cleaner burning "STICK" powder to a Dirty as hell "BALL" powder! and added the NEVER needed it Forward Assist and the Shoulda always had it Chrome lined chamber and Barrel! The Red clay had little if anything to do with it, but the Humidity and steel Cased ammo as well as Mr Red Rust had a LOT to do with it! We were using steel cased ammo, similar to wolf? I'm not calling you wrong, I just had no idea... Read up on it, yes it was not wolf but was US made steel cased ammo, if you look at photos from the time you can see OD green belted ammo hanging from M-60s and so on. But even at that if it were brass case and there was some of that too the Moisture and corrosion would have been similar!

I know LCAAP researched and designed a steel 5.56 case in the mid-70's and it was tested @ Aberdeen, and approved for use in certain climates,  but it was never actually came to fruition. It was around the time they were considering using aluminum cases for 5.56 and the steel was proven to be better for a number of reasons.  I'm not aware of anything actually making it out into the world other than brass for 5.56 from LC or TW.

Quoted: EDIT: Ok, now its time for some Google-fu to try and answer your questions.  Better grab another cold one, I did. Here's an M16.  Not A1, A2, blah blah, just original M16, circa 1965. world.guns.ru/assault/m16.jpg Note the extremely thin barrel, "3-prong" flash hider, and "slab side" upper reciever with no forward assist or brass deflector.  This was the variant initially shipped to Vietnam and advertised as a "self cleaning rifle".  The self cleaning rifle promptly met up with the red clay of 'Nam and got itself an awful reputation in a hurry.

Duke, I thought "slab side" refered to the lower reciever and the raised around the magazine release to keep it from accidentally being pressed. That picture definitely looks like it has a raised area around the mag release. I have an early SP1 that doesnt have this and always thought that was considered slab side. Im not saying you are wrong. I am just curious as to what "slab side" really means now.

Quoted: Duke, I thought "slab side" refered to the lower reciever and the raised around the magazine release to keep it from accidentally being pressed. That picture definitely looks like it has a raised area around the mag release. I have an early SP1 that doesnt have this and always thought that was considered slab side. Im not saying you are wrong. I am just curious as to what "slab side" really means now.

I think people tend to refer to both uppers and lowers as "slab side".  I didn't want to get into the various configurations of early lowers because, well, I've been writing enough already.  Basically there are three variants, "slab side", "partial fence" and "full fence", as described in this thread:

Arfcom Lower Reciever FAQ and Clone Building Guide

There are some really cool pics in that thread of some really old but neat variants of the AR.  The partial fence lowers are the rarest and I've never seen one in real life.  Very quirky stuff, check this one out, the Colt 608 "Survival Rifle" for aircrew:

Thats what I love about this forum. I learn something every day about my beloved black rifle!!!!

Of course, now we need pics of your SP1.  Hehe.

Here's my "Vietnam A1 clone" which is a mishmash of parts from various places, but its configuration is intended to emulate what our troops would have been shooting around the time of the Tet offensive in January 1968.  It isn't an old SP1 but it didn't cost what an SP1 costs these days either.  

Mine:


1968:

Not an SP1 but it IS "mostly" M-16... top, the 20 inch, I have had for a while, the lower came from Tactics LLC "Partial" fence

The bottom one is my new project! The GAU-5/A/A (XM-177) I still have to rework a barrel Ultralight, 11.5" with a 4.5" Fake "Moderator" reparked Gray, Throw the Flat Delta Ring on it (It is in the safe with some other parts and such) Looking for a Chrome Bolt and Carrier if anyone knows where I can get a couple let me know!
Prefer with no FA teeth...

I carried a GAU-5A/A a LOT and I NEVER needed the Forward assist!!! I dont even understand "SPORTS" Slap the mag, Pull the Charging Handle to the rear, Observe the failed, spent, hungup or what not round being ejected, Release the Charging handle, Tap the Forward Assist??? WTF? no time for that BS!!!!

"SMACK, RACK, and FIRE!!!!" Dammit!

SMACK the magazine! RACK the effing BOLT, FIRE the Goddam weapon!!!!

Quoted: Of course, now we need pics of your SP1.  Hehe.

If I knew how. Mine is a pretty good copy of a early M16A1. I also have an A2 style, M4 style and A4 style. Yeah, I love the military guns. Especially the Black Rifle.

Well, that problems solved.

Welcome to the site and the Missouri Hometown Forum.

Thanks to all for the research, and DUKE, man I'd like to see what kind of work you produce when you are actually getting paid for it.  Your insight and in depth coverage of this for me was amazing.  Thanks again guys!!!

Here's a great old article for your enjoyment.  I've read it a thousand times and it just keeps getting better!

Photo caption, first page: "The Moral: If your a police officer trying to stop a getaway
                                     car, shoot fuel for the fuel tank."

AFSOC I think I'm gonna have to copy that little carbine you have there, that thing looks light and nible  Anybody have a cheap A1 upper they'd like to get rid of?

Polytech

HEIT_APDST, thanks for posting that article.  It was very informative.  I will remember to always shoot for the gas tank and will keep 60 rounds on hand in case I need to carve a hole in a concrete wall and crawl through it.

The guy on the third page pistol shootin the AR looks like the T-1000 (Robert Patrick).

Thanks for all thread info, sorry for the slight hijack.

Continue, I am pleased.

Quoted: Quoted: The guy on the third page pistol shootin the AR looks like the T-1000 (Robert Patrick). I have a 20' skinny barrelled rifle and it is not easy to hold it one-handed like that and make 50yd shots on 8" steel targets. I can't imagine how difficult that would be with a HBAR.

You may need to move up from the 32oz descending sets curls!!!

I just got mine out and tried it, I think we need to have a shoot off with them that way!!!

You, Me and Duke!

Oh and the little carbine ain't done yet, the upper is off my latest acquisition! a CMMG trashcan gun! Whole reason I bought the thing was for that upper!!!
The lower that came with it is already sold, the barrel is crap so it will be replaced it is chrome lined but of unknown origin and the front sight pinning leaves a bit to be desired!!!



The upper rear boss hole is eggshaped a little bit the front hole is Large so it is SP1 upper apparently. has an offset bushing in it. Somewhat annoying but I can deal with it.
Looks right. Have to custom mix some norrells in Sandstorm Gray and match the upper and lower, the barrel is to be a Bushmaster superlight not a slight to CMMG but I want it light under the sight too (for the look mostly) the barrel will be cut down in our shop re-threaded Bayonet Lug removed and then blasted and reparked in a lighter gray Zinc finish, along with the handguard cap and flash hider I will have to turn a grenade ring for it as well, the flash hider will come from Bushmaster. The Aluminum stock boot is going to be re-coated with a polyvinyl material OR Gloss Norrells for the right look. Charging handle will be gray and the delta ring will be gray.  The Handgrip is original A1 or M-16 style could probably stand a coat of ..... Something.... but I don't know what yet.

Quoted: Quoted: The guy on the third page pistol shootin the AR looks like the T-1000 (Robert Patrick). I have a 20' skinny barrelled rifle and it is not easy to hold it one-handed like that and make 50yd shots on 8" steel targets. I can't imagine how difficult that would be with a HBAR.

Keep in mind that the article is from 1962. These guys are use to carrying M-1 Garands and M-14's all day. An AR-15 must have been something right out of a Sci-fi magazine to them.

from the article:

"traveling at a terrific speed, 3300 feet per minute."

wow.. 55 feet per second.

Better hope those crooks arent armed with HE nerf rounds

Quoted: Quoted: AFSOC I think I'm gonna have to copy that little carbine you have there, that thing looks light and nible  Anybody have a cheap A1 upper they'd like to get rid of? Polytech I can get my hands on a box full, with handguards and barrels.  I'd have to check on the price.

Well keep me in the loop if you would

Polytech