5.56 or .223, or both?

[SteveG66]

I have a Bushmaster AR15 DCM, I have some 5.56 ammo, from what I have been reading on here and other boards, you should not run 5.56 ammo in a gun chambered for .223 as the 5.56 is a hotter round.

My DCM, according to the Bushmaster website, lists that the caliber is .223 or 5.56. Do they mean the two are interchangeable in this barrel and that I can safely shoot both. It seems that its obvious, but, I don't want to assume that I can and ruin a fine shooting barrel.

Any help or suggestions would be greatly appreciated.

Steve

 

[Serial Crusher]

I'm not sure if Bushmaster has a special chamber spec with a different leade, which the distance from the throat to the riflings so it can do it without harm. I would imagine the worst case would be lost accuracy and barrel life. I think that the 5.56/.223 marking is on a lot of their lowers, and may have nothing to do with the upper or barrel.

5.56x45mm NATO - Wikipedia, the free encyclopedia

 

[SamW]

SAAMI Spec. pressures are higher on the 5.56 and thus, 5.56 chambered barrels can safely shoot both the 5.56 and .223

Most AR's are chambered in 5.56 or a .223 Wylde, which is 1/2 way between the two. .233 specific chambers are used for target guns to be able to load the bullet much closer to the lands.

 

[rambone]

I wanted some clarity on this as well. Too much conflicting information out there.

Are there any AR-15's that will fire one but not the other??

 

[esrice]

Are there any AR-15's that will fire one but not the other??

Yes.

Typically, your carbines are chambered in 5.56, and therefore can run either ammo.

Target/Match/Varmint type ARs are sometimes chambered in .223 and can only shoot .223.

 

[Fergy35]

Esrice is right on with his description. Basically, if it is chambered for 5.56, it will handle both. If it is chambered for .223, it should only be fed .223.

 

[VN Vet]

The ammo chambered for your AR is given (usually) on the left side.

 

[KokomoDave]

Or marked on the top of the barrel near the front sight or gas block.

 

[hc4sar]

Has anyone looked at 6mm.com ? lots of info there take a peek

 

[wizard]

From the DPMS web forum,
While the 5.56 mm and .223 cartridges are very similar, they are not
identical. 5.56 cases are made from thicker brass than .223
cases, which reduces the powder capacity,
and the NATO specification allows a higher chamber pressure. This difference accounts for upwards of 20,000+ psi
difference in pressure measurements. The 5.56 mm chambering, known as a NATO or
mil-spec chambers, have a longer throat, which is the distance between
the mouth of the cartridge and the point at which the rifling engages
the bullet. The .223 chambering is
allowed to have a shorter throat, due to lower chamber pressure.


Using commercial .223 cartridges in a 5.56-chambered rifle should
work reliably, but generally will not be as accurate as when fired from
a .223-chambered gun due to the excessive throat.
Using 5.56 mil-spec cartridges in a .223-chambered
rifle can lead to excessive wear and stress on the rifle and could potentially be
unsafe.


All DPMS rifles give the correct chambering stamped on the base of the barrel. If the base of your DPMS barrel is stamped as 5.56 you may use either type of ammunition, if it is stamped .223 you should only use .223 ammunition.

 

[boman]

Has anyone looked at 6mm.com ? lots of info there take a peek

Great recommendation! It's been of my regular visits on the internet for awhile.

Steve

 

[gotguns]

My bushmaster AR will fire either. It is stamped 5.56 NATO just in front of the front sight. The lower says 5.56/.223 but as was said earlier that doesn't mean the barrel is rated at that. Check it and see. Don't want to ruin an AR or more importantly a left hand.

 

[car06281]

5.56 or 223

I have talked to both Remington and Bushmaster tech support people on this issue. Remington says use 223 only. Bushmaster says they designed a longer lead to accommodate the additional 5.56 pressure.

I have a Bushmaster R15 VTR that I fire both rounds in with no problems (it says 223 only on the barrel). Two things to look for are damaged primers (punctured or flattened) and bright discoloration around the casing neck which indicates excessive pressure and temperatures occurred. If either of these are observed you should only fire 223 ammo.

 

[theturtle06]

Great recommendation! It's been of my regular visits on the internet for awhile.

Steve

when I type in MARYLAND METRICS 'HOME PAGE' I get Maryland Metrics! I think I may have found what you are referring to, www.6mmbr.com ?

 

[bw210]

From the DPMS web forum,
While the 5.56 mm and .223 cartridges are very similar, they are not
identical. 5.56 cases are made from thicker brass than .223
cases, which reduces the powder capacity,
and the NATO specification allows a higher chamber pressure. This difference accounts for upwards of 20,000+ psi
difference in pressure measurements. The 5.56 mm chambering, known as a NATO or
mil-spec chambers, have a longer throat, which is the distance between
the mouth of the cartridge and the point at which the rifling engages
the bullet. The .223 chambering is
allowed to have a shorter throat, due to lower chamber pressure.


Using commercial .223 cartridges in a 5.56-chambered rifle should
work reliably, but generally will not be as accurate as when fired from
a .223-chambered gun due to the excessive throat.
Using 5.56 mil-spec cartridges in a .223-chambered
rifle can lead to excessive wear and stress on the rifle and could potentially be
unsafe.


All DPMS rifles give the correct chambering stamped on the base of the barrel. If the base of your DPMS barrel is stamped as 5.56 you may use either type of ammunition, if it is stamped .223 you should only use .223 ammunition.

Yes, Yes, and Yes.

Check your barrel. Do not rely on the "lower" markings - JMO

 

[boman]

I think I may have found what you are referring to, www.6mmbr.com

yes---great site

Steve

 

[fireball168]

Forget what it says on your barrel - check your chamber.

Buy a Hornady/Stoney Point tool, and measure your throat length, or buy a pound of Cerrosafe and make a casting of the chamber.


If you ever get bored, call Clymer or PTG and ask how many different 223 Remington prints they have that say (Armalite, DPMS, Bushmaster, Rock River Arms, etc. after the name).

Everybody has their own version, I haven't found one yet that has a SAAMI length throat in it - they're all at least as long as the 5.56.

 

[wizard]

hc4sar,
Thanks for the info on 6mmbr.com good site havn't seen that one before.