AR-15 barrel recess

[Copter Doctor]

I've been looking at AR-15's. I have my eye on a Bushmaster, but am unfamiar with the recessed area in the barrel between the front site and flash suppressor. What gives? I'd think this would be a 'weak' spot (subject to heat stresses) in the barrel. Yeah, I know, I'd have to do a lot of shooting to get the barrel that hot.

[billamj]

It is meant as a mounting point for an M204, I believe that is the correct designator, grenade launcher. Standard for any M4 really so it is nothing to be concerned about unless you have a 204 and don't have the mounting point.

[Xringshooter]

As Bill said, it is for a grenade launcher (M203 or equal) to be attached if you are so inclined. IIRC the M204 is the stand alone grenade launcher (I could be wrong and someone will correct me). I've never heard of the cut down portion being a problem.

[RCN]

Xring - correct M203 launcher

Cut down portion generally only present on AR-15 style Carbines not Rifles

See Pic.

[david1]

How safe is it to shot a .223 round from a ar 15 because the ar is chambered for 5.56 round. If you are just target shooting does this really matter or will a .223 round work without problems?

[Legion_Prime]

Current issue is the M203, M204 is what is slated for a replacement which can be attached to a frame (sort of I'm glossing over a bit) so it can be used independently. .223 Remington in a 5.56 chamber is GTG. 5.56 milspec is loaded to higer than SAAMI specs and is not a good idea to use in a .223 chamber.

[RCN]

Off topic somewhat.

I was tracking the M320 as the replacement to the M203. See attachment (other info on new weapons also SASS and others) and links. I am having trouble nailing down the M204 nomenclature. I find some references and bad links for a launcher and some references to a standalone unit. I am not familiar with an M204 launcher in the Army inventory.

Army Times

Armada International

Strategy Page

[billamj]

Off topic somewhat.

I was tracking the M320 as the replacement to the M203. See attachment (other info on new weapons also SASS and others) and links. I am having trouble nailing down the M204 nomenclature. I find some references and bad links for a launcher and some references to a standalone unit. I am not familiar with an M204 launcher in the Army inventory.

Army Times

Armada International

Strategy Page

RCN, no need to worry too much about the M204 nomenclature. I just don't remember all of the nomenclature of today's military because I haven't been in for almost 20 years. During the day I could tell you whatm where and when. Today, not so much.

[Xringshooter]

My bad. The stand alone unit (40mm grenade launcher) was the M79.

[SuperMoose]

How safe is it to shot a .223 round from a ar 15 because the ar is chambered for 5.56 round. If you are just target shooting does this really matter or will a .223 round work without problems?

.223 is safe to shoot out of a barrel marked 5.56
5.56 is NOT safe to shoot out of a barrel marked .223

The difference mainly resides in the pressure of the cartridge after it is ignited. 5.56 is a much higher pressure and if used in a .223 barrel could result in it blowing up in your face. The cartridges are similiar but not exactly the same as some people will lead you to believe.