Exploding M-16's ????

[Tom in GA]

I was at the range a couple of dys ago shooting my Colt HBAR (1:7 twist)when one of the other shooters at the range told me that I was shooting dangerous ammo. The ammo was standard 55 grain NATO stamped ammo made in Isreal. He said that the bullet was too long for a commercial chamber and it would cause excessive pressure and ...kaboom!!! I have not seen any warnings or articles on this problem. Am I missing something?

Information

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[limazulu]

5.56 military ammo fits military chambers that are typically larger than .223 chambers. So, theoretically you could end up jamming a hot loaded military round in to the rifling of a .223 chamber which would significantly increase pressures.

Discussions of this have occurred in the past on Jouster and I don't think anybody came up with an example of that happening. But rather than guess, just take a magic marker to the bullet of one of your cartridges, chamber the round (preferrable not indoors), remove the round and see if there are any marks on the bullet. That will tell you if it's touching the rifling.

[jjroth]

is it 5.56 or.223.
Colt Hbars are NORMALLY the NATO (MilSpec) chamber.

If .223 then chambered per SAAMI specs.

Contact Colt with SN and confirm chambering.

[Jim K]

The bullet has to be forced into the rifling in any event, and there is no significant pressure difference whether there is a long leade or none. In fact, most match barrels are made with a short or no leade so as to minimize the "skid" when the bullet hits the rifling. Bullet skid can cause inaccuracy.

The amount of leade is usually determined by the ogive of the bullet(s) to be fired in that barrel, not out of concern for pressure.

Jim

[Tom in GA]

The Colt HBAR in question is marked .223 and was purchased new in 1990.

[KarlKW]

I think that your shooting colleague was trying to warn you that Israeli 5.56 x 45 mm has a reputation for being loaded "hot." The only split case that I have ever shot was an Israeli round. You may never have a problem with it, but I did. HTH, Karl

[Col. Colt]

As a Colt Armorer, I have never heard of a Factory Colt HBAR shipped with a .223 commercial chamber. If Colt ever did use a commercial .223 chamber, it would have been long ago, in the very beginning - although I do not believe they did. The reciever marking may have been an attempt to "Commercialize" a controversial "Assault Weapon" and make it seem "less military". On the top of the barrel in front of the front sight should be a stamping with the military designation - 5.56, C (chrome) and MP (proofed and Magnetic Particle inspected) and 1/7 (twist) - in which case it is totally safe to shoot with any NATO spec 5.56 Military round. I would assume that the Israelis would adhere to that spec, and what the commentator saw was a bright muzzle flash and sharp report from a real, full power 5.56 NATO load. Most US commercial is a little light.

Colt's chambers have long been MilSpec, and they did not offer a "Commercial chamber" as did some of the clones. You could ask over on AR-15.com if anyone there knows of an exception. How is your barrel marked?

And the only way I know to "explode" a Colt AR is to leave out the bolt cam pin on assembly (DON'T!!!!!) or plug the bore.

[drshame]

I had a squib round unknowingly block the bore of a Colt USGI A-1 upper.
The next round blew out the bottom of the magazine from the back pressure.
Got my attention.
The barrel's fine and still shoots great with no apparent ill effect..
It was a testament to a very good design and my need to greatly improve my reloading.
AR's don't blow up unless idiots don't pay attention to what it's being fed.

[Brad in Idaho]

On the top of the barrel in front of the front sight should be a stamping with the military designation - 5.56, C (chrome) and MP (proofed and Magnetic Particle inspected) and 1/7 (twist) - in which case it is totally safe to shoot with any NATO spec 5.56 Military round.

Colt's chambers have long been MilSpec, and they did not offer a "Commercial chamber" as did some of the clones. You could ask over on AR-15.com if anyone there knows of an exception. How is your barrel marked?

My Colt H-BAR is marked as you describe except it is 1/9 twist. My question is, when you reload for a 5.56 chambered rifle, should the overall length of the finished cartridge be longer than for a commercial chambered .223?

Sorry if it's a dumb question, I'm a novice at handloading.
I'm getting components and tools together to start reloading for my H-BAR and I want to get it right.

[Col. Colt]

Brad, there are no dumb questions - it's only dumb when you fail to ask and get yourself in trouble due to pride!

Many Match handloaders tailor there accuracy loads to the individual chamber by seating the bullet to the "most accurate" length. You would want to be pretty advanced in your handloading knowledge and practice before you attempt this, and special tooling is recommended.

I suggest you read up on the subject extensively and talk to some advanced loaders, but until you feel competent, stick with the specs in the Handloading Manuals. (Also, an AR has a maximum length due to the magazine itself to consider.) Get ahold of Zeddiker's (sp?) book "The Competitive AR15" and give it a read - it will explain. Cheers, CC.