What is the difference between an A3 and A4 upper?

Thanks,

Quoted: A1   Seriously in the civlian world there is no difference, just different marketing terms.

LOL, A1.  That's funny.

BTT.  Just like Forest said.  There is no difference out here.  They're just terms.

A4 = gas block, no front sight.

Quoted: 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
www.armalite.com/ItemForm.aspx?item=15A4CBA2K&Category=8e8e5de6-5022-483e-812b-822e58014822%20&ret_url=Categories2.aspx?Category=8e8e5de6-5022-483e-812b-822e58014822

Quoted: Quoted: 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.

By the .mil standards, the A3 is the same as an A2, fixed carry handle, rear sight adjustable for windage and elevation. The A4 is a flat top upper that does not have the M4 extended feed ramps.

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?

Quoted: 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?

Where?

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.

i know i have an A4 upper and it is just a flattop upper that happens to have an A2 fsb (the classic looking triangle front sight) and carbine length handguards

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

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

please correct me if i'm wrong

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

Some info here...

www.biggerhammer.net/ar15/uppers/

Can't vouch for it's validity...

Quoted: What is the difference between an A3 and A4 upper? Thanks,

Nothing.