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6/26/2007 10:40:52 AM EDT
I have an Armalite AR-15, marked- Carbine 5.56 mm, M4C. It is a 16" heavy barrel, chromed bore and it was made in Nov. of 1997. I contacted Armalite and asked them if they could confirm the chambering, either 223 (SAAMI)or 5.56 Nato, based on the serial # and model. They could not and said I would have to ship the upper to them for them to inspect and determine it. Anyone have a similar carbine and can answer the question? I have shot surplus 5.56 and reloads without a problem but I understand there could be if it is a 223 chamber.
                                                                                    thanks
6/26/2007 11:33:15 AM EDT
[#1]
Or you could take it to you local gunsmith and have them make a cast of the chamber.  Then measure the length of freebore on the cast and compare it to the 'spec.
6/26/2007 12:26:54 PM EDT
[#2]
What's the barrel length?  What's the upper?

I believe the M4C had a 14.5" barrel with a pinned flash suppressor.

Hardwarz
6/26/2007 12:56:57 PM EDT
[#3]
It did indeed have a pinned muzzle brake, which I removed and replaced with flash hider.  The upper is an A-2. As to the barrel length, what is the measuring point on the receiver end? From the front of the carry handle to the end of the barrel thread, it is around 15.5 "'
6/26/2007 1:01:54 PM EDT
[#4]

Quoted:
. what is the measuring point on the receiver end? .'


From the bolt face to the end of the barrel (or muzzle device if the device is permanently attached).  You'll need to drop a rod down the bore.

Generally from Armalite at that time you'll be looking at 16" or 20" barrels.
6/26/2007 1:13:23 PM EDT
[#5]
Forrest
Dropping a rod down the barrel and measuring from the bolt face to the end of the barrel threads, it is a 16" barrel.
6/26/2007 1:17:28 PM EDT
[#6]

Quoted:
I believe the M4C had a 14.5" barrel with a pinned flash suppressor.


Not in 1997 - a muzzle brake perhaps, but no flash supressor.

Haze,
Honestly the only way to be 100%sure is get a chamber casting (or do it yourself - IIRC Brownells sells the kits).  It's the only way I know to measure the leade - the other way is to get the 5.56 reamer Pat Rogers mentioned in SWAT a few months back.  If you see metal comming out when you use it then you'll know it' wasn't a 5.56 (but will be when you're done).
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