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Posted: 6/25/2004 2:12:23 PM EDT
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I have a Colt barrel and I am trying to figure out if it is chrome-lined. The flash hider is on there very tightly (possibly loctited) so I can't get it off. Here are the details: 16" M4 profile, preban (lug and A2 flash hider) Marked C MP 5.56 NATO 1/9 9/99 date stamp behind the FSB The base of the chamber, right next to the ejection port, has a small "4" stamped into it. The chamber is clearly chrome lined (I can see the ring). On the muzzle, inside the flash hider, is a rough, somewhat irregular ring surrounding the crown, a little under 1mm wide. This looks like it "could" be the end of a chrome lining, but it is thicker than the one I've seen on postban Bushmasters. It also looks more black than grey, even after I cleaned it with Q-tips. The bore looks dull grey when I shine a flashlight into it, and it does not collect copper like my old non-lined barrel even though I use CLP and not copper solvent. I think it probably is chrome-lined. However, Troy has said that Colt turned a bunch of non-lined 16" HBAR barrels down to M4 profile to meet Y2K demand, and mine has a 9/99 date stamp. What say you? |
No, the "C" on the barrel stands for "Colt"  Because it's at the front of the line. Not familiar w/current Colt markings, but historically if it had a "B" or "chrome bore" at the END of that line, it's was chrome lined all the way ("C"at the end meant chrome chamber only)dbrown, take a Q Tip with some instant blue on it, and dab that ring at the muzzle. If the ring turns blue, it's not plated. If it doesn't take the blueing. it's chromed all the way
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Your right (just looked at mine) it also has the "B" on it. |
I have a XM177E2 barrel that has 'C MP C' stamped on it and it is fully chrome lined. I have seen two other XM177E2 barrels that have the same markings as mine and have full chrome lining. I also recently had and sold 3 M16A1 barrels that said 'C MP C' and were fully chomed. |
These are all 30+ year old barrels. Barrels made since the early 80's are stamped as above. Generally, Colt's HBAR or 1:9 barrels made since 1997 are NOT chrome-lined. The 1:7 barrels with a military profile (M4 or 20" A2) ARE fully chromed. -Troy |
Gee, who am I to argue with an expert  All I know is what I 1) have experienced and 2) have read, which confirms my personal experience.Gee, 6 Colt barrels in a row that were fully chromed with only a C at the end. Probably a record for Colt violating their own specs
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I always wondered about mine, but always felt dumb asking....They look chrome lined, but according to the stuff on biggerhammer.net, they aren't. I have early Colt LW barrel stamped CMP 556 nato 1/7 police upper stamped cmp 556 nato 1/9 HBAR and a frickin nesard barrel with no markings....... |
It's not a police upper - it's on a Colt frankengun (all Colt parts) that a USMC officer sold to me 4 years ago. Slabside AR-15 lower w/ large pivot pin, A2 upper, but the barrel has a 9/99 build date, so it was made after the ban but is a "pre-ban" configuration. |
It's common knowledge. Colt's 1:7 barrels are considered "military/police" barrels and are chrome-lined. Their 1:9 barrels are considered "civilian" barrels, and Colt stopped chrome-lining the bores (but not the chambers) of these barrels in 1997 as a cost-savings measure. Not to be an ass, but do you see the title and post count to the left? You think there might be a reason for them?  -Troy |
I just like to know where information comes from, that's all....that and I am still getting used to the site. Gun folks are some of the most opinionated people I know, and not all folks base their opinions on facts. Here's one for you then, the above barrel of mine is on a "Law Enforcement Only" gun, therefore it would fall under the "police" instead of civie headings for colt...bought as a department group purchase in 1996.....only markings are cmp 556 nato 1/9 Hbar....It sure looks chrome plated...what say you? |
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So if I understand all this correctly: If I've got a Colt R6721DC conversion kit that I purchased in 1998. It's got the 1/9 barrel marked "C MP 5.56 NATO 1/9 HBAR" and is stamped "7/97" behind the FSB. It's got the M4 marking on the ahead of the flattop rail and the M4 feedramp cuts in the receiver. It sounds like the barrel would not be chrome lined? Thanks, Don. |
The price for Colt uppers (and parts) is insane. I bought my 6920 upper conversion from Hoplite, and the next week it went up about $150. That was several years ago. I love Colts, but no way in hell I'm paying that much for an upper now when you get a good quality AR for much less than $900. Kevin |
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squeezecockerp7m8: I hear ya. This damn thing has been sitting in my safe since '97 waiting for me to have both the funds and the time to put it together with a lower and all the bling-bling stuff and now that I'm finally ready to go I find out it's probably not the upper I want to use anyway! Ha, ha, live and learn... I'll probaby put it up for sale and try to pick up a LMT M4 upper for my project. |
I've got a pre-ban 6721 upper I believe is the same as yours on my Lightweight Sporter Lower. I bought it this way assembled, and can't find a date code on it anywhere. Mine has the exact same barrel stampings as yours, and was told it was a nearly new 6721 Tactical LEO upper. It has all the usual C AF markings on the upper as well as the M4 stampings. I had mine at the range for the first time today and several FTE with brand new Q3131A Winchester rounds. I was wondering myself whether these had chrome chambers and/or chrome bores?? I'm an admitted newB to these intricacies but trying really hard to learn. About 20 rounds of the 140 I shot today wouldn't come out of the chamber after firing. It looks clean, and straight and still very new. I took the bolt all apart at the gunsmith counter of the shooting range afterwards, and they even said all the internals looked OK. When it cycled correctly, and shot as it was supposed to, it shot GREAT. Then out of nowhere a round wouldn't eject, and it tried to drive a fresh round in on top of it. It was DAMN hard to get the rounds out too!!! The ejector was clean, smooth and functioning normally. I JUST got the gun back from Wilson Combat for a matching grey finish of Armor Tuff on the upper only to match the Colt grey lower. The guy working at the range said it "could" be a little AT finish got in the chamber and is keeping it from releasing the shells right. The spent shells showed no markings at all of ejector problems or swelling at all. It's like they just didn't want to release from the chamber ...??? I bought a chamber cleaning brush and am going to clean, clean, clean it up and see if that helps, since everything in the bolt is operating smoothly. Any helpfull hints at chamber scrubbing???? ANY IDEAS FROM YOU VETERANS????? |
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JETWC: I'm probably more of a newbie than you are so I can't tell you much; I'll be waiting along with you to see what the veterans have to say. As far as I know the only "date" information available on the barrel is a date code a la "7/97" that is stamped on the barrel just behind the FSB (i.e. on the chamber side of the FSB). So you have to remove the handguards to see it. I don't know if stamping that date code is common practice or not. If you take your handguards off do you see anything in that area? Also, I'm curious, did you have any similar extraction problems with your rifle prior to having it refinished? |
I've not had the handguards off yet. I guess now I Know where the date code is. Unfortunately I didn't get a chance to shoot it before I got the upper refinished. I really haven't had it that long. It just looked goofy in the 2-tone black over grey I bought it in. The Armor Tuff is very close to the stock Colt grey finish. I'll figure it out, but I'm sure Troy and the other vets will have an answer. |
I am not trying to argue with you. Just stating my personal experience. |
| Ok, whatever the ring is around the crown, it does not respond to an overnight soak in CLP, MP7, or being gently scraped along the edge (away from the crown) with a precision scredriver. Not even a black mark on the Q-tip when I wipe it after being soaked. So it looks to me like the end of a chrome lining, not crud buildup (which would be unusual at that location anyway). |
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dbrowne1: Do you have another AR15 known to have a chrome lined barrel that you can compare it to? When I glance at my 1/9 barrel I can almost convince myself that I see the chrome flashing or ring or whatever you want to call it at the end of the barrel. But when I place my 1993 era 6601 with a 1/7 barrel next to it and focus a bright light on them it is quite noticeable the difference. The chrome ring at the end of the 1/7 barrel is obvious and in comparison the 1/9 barrel just doesn't look the same. Edited: Woo hoo! This is my 100th post. Can't believe it took me over two years to get there! I need to get out more. 
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I'll see if I can find someone else with an old pre-ban Colt barrel. The main problem is that I can't get the flashhider off, so even with a Surefire shining in there, it's hard to tell, and I can't take a photo. There is a mark on the stepdown from the bbl extension to the barrel as well - very deep, rough stamp, looks like a C or an O. |
Yes. GC's are (pivot-pin excepted) made to government specs, and besides, they were made years before 1997. Oh, and some pics:  Chrome around the breech indicating a chromed chamber.  Chrome around the muzzle indicating a chromed bore -Troy |
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