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Discussion Starter #1
I have a preban Colt H-bar Sporter that is labeled 5.56 on the barrel but .223 on the lower. Which is it? I have looked around online and found that Colt makes only 5.56. I have also read that many manufacturers often mislabel their firearms in this case. The reason this comes up is because my gun refuses to shoot 5.56 rounds it repeatedly fires and ejects a round but fails to chamber the following round, in addition to this it also will pop primers making me think this chamber is in fact a .223. Does anyone know for sure which it may be? If it is a 5.56 why is this happening?
 

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There IS a difference in the .223 chamber and a 5.56 chamber.

If I remember correctly, 5.56 chambers are usually built heavier for higher pressures and will feed either 5.56 or .223 ammo. (at least all of mine do)

A true .223 chamber will not work properly or safely with 5.56 ammo. Head space may be an issue. I don't know about the feed ramp...

It sounds like you have a .223 chamber and a 5.56 barrel. But that is just my guess.

Here is a good link on the issue.
http://www.fulton-armory.com/556-vs-223-Chambers.htm

TA
 

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moonglorious61 said:
I have a preban Colt H-bar Sporter that is labeled 5.56 on the barrel but .223 on the lower. Which is it? I have looked around online and found that Colt makes only 5.56. I have also read that many manufacturers often mislabel their firearms in this case. The reason this comes up is because my gun refuses to shoot 5.56 rounds it repeatedly fires and ejects a round but fails to chamber the following round, in addition to this it also will pop primers making me think this chamber is in fact a .223. Does anyone know for sure which it may be? If it is a 5.56 why is this happening?
I'm a long time Colt AR owner and had six preban Colt rifles and carbines before and the thing with Colts are that the chamber size are marked on top of the barrel which in your case 5.56, the markings on the lowers are just old rollmarks that Colt never changed, ignore the lower markings.

Is your Colt H-BAR a rifle or a carbine?

My current Colt LE model AR6721 AR-15A3 tactical carbine is marked 5.56 on the barrel but .223 on the lower receiver and I always use surplus 5.56 ammo and no problems.

The problem that you described is short stroking and there could be a number of things causing it like gas leak, the bolt carrier group dragging during the recoil cycle, buffer and buffer tube problems, etc.

The only time I had a similar problem with my former Colt R6600 AR-15A2 H-BAR Sporter rifle was I had a lot of powder residue and carbon inside the bolt carrier and the problem went away after I cleaned inside the carrier and behind the bolt.

Colt have a lifetime warranty and I would suggest contacting Colt customer service at the factory and tell them about the problem so they could fix it.
 

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Discussion Starter #5
This rifle is 20in and originally had a A2 buttstock which I replaced with a Bushmaster adjustable. The problem occurred before and after this change. The issue, I would think, is not related to cleanliness since everything is spotless, sans the gun oil. If it is the bolt carrier group dragging during recoil why does it function perfectly with .223 rounds (with goods groups) but can't cycle the 5.56? Hey Texas, this site has a lot of information about the subject as well http://www.ammo-oracle.com/body.htm#diff ... NUTFINN might wanna check that out too.
 

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moonglorious61 said:
This rifle is 20in and originally had a A2 buttstock which I replaced with a Bushmaster adjustable. The problem occurred before and after this change. The issue, I would think, is not related to cleanliness since everything is spotless, sans the gun oil. If it is the bolt carrier group dragging during recoil why does it function perfectly with .223 rounds (with goods groups) but can't cycle the 5.56?
The problem happened before and after the collapsible buttstock change, which means the defect originally came from the factory?

It's hard to diagnose problems like yours in the internet without actually looking at the hardware, maybe try different M855 5.56 62gr ammo and different USGI magazines and see if the problem could be fixed that way.

5.56 M855 should be more of a hot load than a .223 cartridge and should have the opposite affect than what's happening to you, but the extra power of the 5.56 might be making your bolt carrier group cycle too fast and sometimes combined with a weak magazine spring, the bolt can't strip the next round from the mag.

A way to slow down the bolt carrier cycle would be to use a M16 bolt carrier (which is legal to use in semi auto AR), and/ or heavier H to H3 buffers, also check that your action spring is not worn out, the uncompressed length of the spring should be within the spec dimensions.
 

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Short cycling can pop primers?

TA
 

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If a Colt barrel then its 5.56 and can shoot either 5.56 or .223. However, most .223 is loaded down compared to 5.56 so some weapons may not run some .223 loads as well.
 

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Texas Armadillo said:
Short cycling can pop primers?

TA
Did I said that? Feel free to quote me, my answers are mainly for FTF condition, you already took care of the chamber problem so I didn't want to repeat that answer.

As with the incorrect chamber dimensions I agree with you that is possible.

Colt already made many 5.56 NATO 1/7 barrelled rifles and carbines called the SP2 Sporters which I previously had in the mid 80s before they made the A2 HBAR 5.56 a year or several years later.

It is possible that there could be factory dimensional errors in only that particular rifle which could be just an isolated case.

Anyway, the original poster should have it looked at by a qualified shop to prevent any other damage or possible accident.
 

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Discussion Starter #10
yeup

I'd say you're right. Thanks for the insight. I think that's about my only option at this point is to have it looked at.
 

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I'd get a set of headspace guages and check your bolt/barrel combo. If popping primers you may have excessive headspace.
 
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