A1



Seriously in the civlian world there is no difference, just different marketing terms.

A4 = gas block, no front sight.

Originally Posted By Hoplophile: Originally Posted By akethan: A4 = gas block, no front sight. Wrong. Even ignoring that companies use A3 or A4 to refer to stripped uppers and not just upper assmeblies. For example: www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=224 www.olyarms.com/index.php?page=shop.product_details&flypage=shop.flypage&product_id=44&category_id=6&manufacturer_id=0&option=com_virtuemart&Itemid=37

Never suggested it was "right".

BTW spellcheck is your friend.

A3 is flatop w/o M-4 feed ramps and A4 recievers are flatop with M-4 feed ramps.

So i am told

but what does that mean?

The M16A2 entered service in the 1980s and fired the NATO standard Belgian-designed M855/M856 cartridge.[2] The M16A2 is a select fire rifle capable of semi-automatic or three-round bursts and incorporating design elements desired by the Marine Corps.[2] These features included an adjustable rear-sight for windage and elevation, a 5/8 inch longer buttstock, heavier barrel, case deflector for left-handed shooters, and rounded handguards.[2] Mode of fire is determined by using a selector switch on the side of the weapon. The M16A3 was essentially an M16A2 with an M16A1 fire control group; this had only limited procurement by the USN. (FULL AUTO)

The M16A4 became standard issue for the United States Marine Corps during Operation Iraqi Freedom, increasingly replacing the earlier M16A2. In the United States Army, a combination of the M16A4 and M4 Carbine continues to replace existing M16A2 Rifles. The A4 incorporates a flattop receiver unit developed for the M4 Carbine, a handguard with four Picatinny rails for mounting optical sights, lasers, night vision devices, forward handgrips, removable carry handle and flashlights.

Originally Posted By chevyrulz: i mean, the term "A4 upper receiver" has nothing to do with the FSB or barrel does it?

No they are different issues in the Commercial rifle world.

i am under the impression "A4 upper receiver" is synonomous with flat-top upper receiver"

That is correct.

i thought A1, A2, A3, and A4 only referred to the sighting configuration (a=aiming?)

Depends on your context Military or Civilian rifle.

A1 or A2 can also refer to lowers, handguards, pistol grips, or buttstocks.

Probably depends on the manufacturer.

Daniel Defense sells both an A3 and an A4 labeled upper. I only have the A4 style in stock. It has M4 feedramps cut into the receiver

Rock River sells one labeled A4. It appears to be from the same forgings (both have the keyhole symbol on them) as the DD but it does not have the M4 Feedramps cut into the receiver.

So A3 vs A4 is probably dependent on who made them

Chad
eguns.com