Question for you AR-15 Pros- article claims NATO ammo dangerous in Armalites?

ED P

I've been waffling between an Armalite M15A2 and a Bushmaster for months, and came across this article at the Fulton Armory website, claiming Armalite chambering may not be sized correctly for mil-spec ammo.Obviously they want to call out the reasons they are doing things their way, that's just part of business, but as someone considering an Armalite AR, is there a serious concern here, or a minor design detail, with little chance of danger, that they're waving as part of why they're better?********************************************Article from Fulton Armory AR-15 FAQ page.******************************************** What's the difference between 5.56MM and .223 Remington chambers in the AR-15r-type rifle?Would someone care to comment on shooting 5.56 mil spec ammo in a .223 SAAMI chrome lined AR? I've heard everything fromyea to nay on other lists and am looking for the voice of reason here. I have an Armalite M15A2 on order that I was told byArmalite would have an M16 Nato chamber (I specifically asked this before I ordered). Now they say all their guns have SAAMIspec chambers but they are going to switch the chrome lined ones to Nato in the future due to customer demand. I know thatSAAMI says not to shoot 5.56 in a .223 chambered gun, but Armalite says it's fine. --ChanceIf we are talking about .223 Remington SAAMI-spec chambers in an AR15, OH NO!Do NOT use such a chambering if you EVER plan on shooting any military NATO 5.56 ammo, which happens to be only the mostcommon, least expensive and most widely used AR15 cartridge available in all the world. In other words, NEVER buy/use a SAAMI-specchamber in a battle rifle, especially if the barrel and chamber are chromed, as you cannot fix it!Here's the problem. Many NATO cartridges have bullets that will become jammed into the rifling of a SAAMI chambering (the throat istoo short). This is VERY DANGEROUS, for a grat number of reasons.Fulton Armory uses a "5.56 Match" chambering in its rifles/uppers/barrels (in fact our barrels are marked as such), which is a slightlymodified SAAMI chamber with a tad longer throat to accommodate NATO bullets. The Fulton Armory 5.56 Match chamber allows for thesafe and reliable use of all SAAMI and NATO ammo, while offering the accuracy potential of the SAAMI chamberings with matchcommercial cartridges. Remember, there's often a large difference between bolt guns and military rifles. This particularly true for the 5.56 vs.223; Fulton Armory is well known for the finest performance for any given platform, and our 5.56 Match chamber is one way we achievethat performance with the AR-15-type rifle.Hope this helps.Best regards,Clint McKee

cpermd

Horse puckeyMore Fulyton Armory PRcpermd

JudgeColt

Let me start by saying I know little about this subject. However, I believe the warning probably applies to the heavy-bullet 5.56 NATO loads like the 62-grain loads. Those bullets are probably longer and may be seated further out so as to engage the rifleing as warned. Someone who knows the specifications for the NATO versis commercial loads please post further information.

oneshy

From what I have read the specs are .008" different between the 2. Case length for the 223 is 1.752". 5.56 Nato is 1.760". Therefore the 2 can be fired in a Nato chamber. But 5.56 should not be fired in a 223 chamber because higher chamber pressure will result.

cpermd

Have you guys ever been to a match and seen Oly SUM barrels,Armalite,DPMS shooting 68-75 grain bullets with SAAMI chambers,throats and necks.I have and do.cpermd

JudgeColt

While I am aware of the situation Doc mentions, I doubt that any of those rifles are shooting anything not specifically loaded for them. Presumably, each shooter has tailored the load to just about engage the rifling, and has trimmed the brass, etc..The case length difference mentioned does give concern. I wonder why the difference? I have used military brass in all my para-military rifles chambered for .223 Rem./5.56 NATO for years without knowing the difference, although I have always chamfered the outside of the case mouth, which may make a difference. I recall one of my Colts says NATO on the barrel. Perhaps Colts so marked are different. I own no ArmaLite .223 rifles so do not know their specifications. I will have to look at the chambering markings on my rifles to verify what they say.

oneshy

During development of the round, which was originally termed 222magnum, it was found that velocity at 500 meters did not meet military specs. By lengthening the case they were able to meet those specs.

Der Gebirgsjager

Gents-let's take a logical (and factual) look at this problem. The 5.56mm was first, developed from the .222 Rem. (not mag.), but made a little longer. In it's final form it is slightly shorter than the .222 Mag. It was specifically made for the Armalite rifle. The .223 Rem. was next, the civilian version of the 5.56mm. Confirm this, if you will, by consulting "Cartridges of the World", Frank Barnes, 8th edition, page 19. Barnes gives a write-up for both versions of the cartridge and shows an overall case length of 1.760". "The Handloader's Manual of Cartridge Conversions" John Donnelly has seperate write-ups for .223 Rem. (Pg. 152) showing an overall case length of 1.760" and the 5.56mm (Pg. 701) showing a length of 1.755. The .223 is, therefore, the longer case, if there indeed is a difference. You will note that Barnes states that the M193 military version with a 55 gr. bullet has been superseded in military service by the SS109 which is loaded with a 62 gr. bullet. On the surface this would seem to be no big deal and no problem; and usually isn't. Where the problem arises is that in civilian chambered rifles (SAMMI-spec) the longer bullet will be in contact with the back of the lands, thus increasing pressure when fired; and if unfired and extracted, sometimes pulling the bullet, leaving it stuck in the chamber, dumping powder into the magazine well, and generally making a mess. I have a 180-series Mini-14 that did this until I figured out I was using the longer bullet (wasn't too accurate either--but that's a different story--rifling twist rate). All current military chambers should handle all versions of the .223/5.56mm. All older civilian and military chambers should handle the .223 and M193 5.56mm, but not necessarily the SS109--although military chambers are generously cut to handle dirty and corroded ammo and may also handle the SS109. The area to be aware of potential problems is SAMMI chambers and the SS109.