View Full Version : COLT A3 #6721 TACTICAL CARBINE
I have a chance to purchase the above. Would a Colt 6920 be a better choice.The A3 has a heavy barrel. It will be used for target shooting .
The 6920 is a 1:7 twist and the 6721 is a 1:9 twist, heavy barrel. The 6720 which is a 1:7 with a lightweight barrel.
Moose-Knuckle
04-25-14, 17:43
OP, don't know how much the 6721 is that you are looking at but GT Distributors have them for $899 in store only.
What kind of ammo? If you want to shoot a lot of 77s, you may be pushing it with 1/9.
HardToHandle
04-25-14, 20:26
I have a chance to purchase the above. Would a Colt 6920 be a better choice.The A3 has a heavy barrel. It will be used for target shooting .
I have a 6721 lightweight which is a pleasure to shoot. I have have found it as accurate as an M4 cut 6940.
Ymmv.
Redbeardsong
04-25-14, 21:20
I have a 6721 lightweight which is a pleasure to shoot. I have have found it as accurate as an M4 cut 6940.
Ymmv.
The 6721 has a heavy barrel. The 6720 is a lightweight barrel
If all you intend to do is target shoot, go with the lower priced carbine. If you do not intend to shoot heavier weight ammunition, the 6721 will serve your purpose. The 1/9 twist is designed for bullet weights of 55gr to 69gr. Like markm said, you will be pushing it with 77gr. I enjoy shooting my 6721. It is accurate. It is a Colt, so you know what you are getting.
plouffedaddy
04-26-14, 16:37
I have a chance to purchase the above. Would a Colt 6920 be a better choice.The A3 has a heavy barrel. It will be used for target shooting .
I think it's a great rifle. If you're going to be humping it around for days the weight may matter; otherwise it's an accurate, reliable gun. My review:
https://www.youtube.com/watch?v=sj6X8HtwejU
Colt 6720
http://www.slickguns.com/product/colt-6720-ar-15-223-rem556-nato-20-rnd-16-lightweight-barrel-flip-sight-4-position-stock-949
LIL-COMMANDO
04-27-14, 14:48
The 6720 or 6721 would be great it just depends on what you want. Cheaper than Dirt has them both for 888.00 including shipping. I picked up the 6720 for the lightweight and 1/7.
I have a chance to purchase the above. Would a Colt 6920 be a better choice.The A3 has a heavy barrel. It will be used for target shooting .
The 6721 is known to have a very accurate barrel. I'm not sure what the reasoning is, but you tend to hear about it often. Otherwise, the 6721 is generally overlooked anymore.
I have a chance to purchase the above. Would a Colt 6920 be a better choice.The A3 has a heavy barrel. It will be used for target shooting .
For your intended purpose, there really would not be a downside to the 6721. Even as a general duty patrol rifle it works well. Mine has been in service for over 15 years and just keeps going.
6720 (instead of 6920 [also excellent btw]) Gets my vote... mostly because I have one and I love it. :D
Doc Safari
06-08-15, 09:41
I got a deal on an AR6721 this weekend ($880.00 retail plus tax). If I'm not mistaken that was the wholesale price not long ago.
Couple questions.
I started doing some research online and found out from a couple of posts on other forums that early ones only had a chrome-lined chamber but not bore.
My barrel is marked C MP 5.56 NATO HBAR 1/9 (may have gotten the order wrong), but I assume that means it was a standard military barrel that they may have just left heavy instead of machining the grenade launcher groove into it?
Since I was reading posts going back to 2007 and 2008 regarding early ones that only had a chromed chamber but not bore I find it hard to believe in 2015 there are still any left in gun shops that aren't fully chrome lined. Still, the gun shop had the rifle marked for $980.00 and knocked a hundred bucks off without even blinking. That, and I got a free Colt cap makes me wonder.
I can see the chamber is obviously chromed. I shined a bright light at the muzzle crown but I can't really tell.
Is there a way to tell from the serial number or maybe some code on the box label?
I find it hard to believe that gun shop just happened to have one of the early ones after all these years, particularly because of all the panic buys since then, but I'm anal and wanted to know for sure.
BTW, the rifle is obviously more accurate than my other M4's. Even just plinking I was hitting targets consistently that would be a tad small for my other carbines to hit.
I think I'm saving the 6721 for a good variable optic.
I find it odd that the receiver is marked .223 when the barrel is obviously marked 5.56. Is this Colt just opting to avoid confusion in the uninformed general public? Did they think most people don't know about 5.56/.223 and decided just to mark it accordingly?
I'm glad Colt installed a plain Jane collapsible stock on this carbine. My girlfriend's Colts have either a Rogers stock or some other type that I can't remember (maybe a MagPul?). I much prefer simplicity.
The rifle also came with a MagPul buis, so that tells me it must be recent manufacture.
All in all I think I'll leave it stock but I may replace the fat M4 handguards with skinny ones.
Based on the extra accuracy and the horsey, it's a keeper.
If it's gonna be heavy I'd free float the barrel and wring every bit of accuracy I could out of it.
MOLON did an accuracy eval of one and it was pretty impressive.
I really like the 6721 a lot. Mine is accurate with irons. I am waiting for a Leupold MR/T M2 to arrive for that carbine.
There were some posts here from a long while back that addressed the chrome v. non-chrome debate. In those posts, it was identified that the chamber is 5.56mm. I can not remember enough about it and can not search for right now. I remember that some of the more knowledgeable members commented on chamber and bore.
Doc Safari
06-08-15, 14:11
I really like the 6721 a lot. Mine is accurate with irons. I am waiting for a Leupold MR/T M2 to arrive for that carbine.
There were some posts here from a long while back that addressed the chrome v. non-chrome debate. In those posts, it was identified that the chamber is 5.56mm. I can not remember enough about it and can not search for right now. I remember that some of the more knowledgeable members commented on chamber and bore.
I think the chamber must be 5.56 because the barrel is marked 5.56.
I can also confirm that the chamber is chromed because you can see that silver halo of plating around the rear of the chamber.
What I could not get a good look at was a corresponding halo of silver at the muzzle. I'm not saying it's not there; I just couldn't get a good look with the lighting available.
When I get a chance I'll run the serial number on Colt's website to see when it was made.
The fact that it came with a MagPul rear buis and a MagPul Pmag makes me think it can't be more than a couple years old, and therefore it's likely that the entire bore is chromed.
I could understand if they left the bore unchromed for greater accuracy potential, but we're talking about an M4, not a sniper rifle.
I look forward to other replies.
interested as well. I have one thats marked Match Target from the mid 90s
I wouldn't worry about it not being chrome lined. It's an HBAR, supposedly built for accuracy.
Free float it, and see what it'll do...
Doc Safari
06-08-15, 17:27
I wouldn't worry about it not being chrome lined. It's an HBAR, supposedly built for accuracy.
Free float it, and see what it'll do...
I consider the chamber being chromed a "must" for reliability. Having said that a non-chromed bore should be more accurate. As I stated above, even just plinking at cans and small objects my 6721 is appreciably more accurate than my Bravo M4 (nothing against BCM just difference in tolerances). I'll take my BCM carbine for everyday work, but the difference in accuracy makes me definitely see the 6721 as a potential platform for a good precision optic.
Bottom line: whether the bore is chromed or not, I just want to know so that I can make a mental note whether or not to keep a good coat of rust preventative in it while it's in storage.
I could understand if they left the bore unchromed for greater accuracy potential, but we're talking about an M4, not a sniper rifle.
The bore of your barrel is chrome-lined. Stop obsessing over it and go enjoy shooting it. Free-floated and using the proper hand-loads, your barrel has the potential to do this . . .
https://app.box.com/shared/static/oapb4ystz8h2ae2smg58o8u5jfdgs5az.jpg
....
I consider the chamber being chromed a "must" for reliability. Having said that a non-chromed bore should be more accurate. As I stated above, even just plinking at cans and small objects my 6721 is appreciably more accurate than my Bravo M4 (nothing against BCM just difference in tolerances). I'll take my BCM carbine for everyday work, but the difference in accuracy makes me definitely see the 6721 as a potential platform for a good precision optic.
Bottom line: whether the bore is chromed or not, I just want to know so that I can make a mental note whether or not to keep a good coat of rust preventative in it while it's in storage.
Yes, chrome is not the best plating for corrosion resistance.
Yes, chrome is not the best plating for corrosion resistance.
I thought chrome was the only plating used for bores and chambers.
On that note, how are they plated? Is it electroplating?
I thought chrome was the only plating used for bores and chambers.
On that note, how are they plated? Is it electroplating?
Chrome is the only bore plating I'm aware of too. I was just pointing out that a chromed surface is still susceptible to corrosion, as is stainless.
Doc Safari
06-09-15, 14:01
Yes, chrome is not the best plating for corrosion resistance.
I have read that chrome plating is not "corrosion proof", yet I've never had a chrome bore corrode. I know that one of the main benefits is that it greatly increases barrel life because it's many times harder than steel.
IIRC one of the reasons the military switched to a chromed bore on the original M16 was to prevent corrosion in the jungles of southeast Asia. So while it may not be foolproof, I take that to mean it's darn near corrosion proof.
Doc Safari
06-09-15, 14:02
The bore of your barrel is chrome-lined. Stop obsessing over it and go enjoy shooting it.
....
I'm not obsessing. I just like to know my weapon's specs. For example, I've been reading up on the advantages/disadvantages of a 1/9 twist compared to a 1/7 twist...just because I want to know.
There have to be reasons why Colt manufactured this particular variant as an HBAR with a 1:9 twist. I'd simply like to know.
Was it greater accuracy potential? The rifle certainly shoots smaller targets than my BCM with a 1:7 twist. I'm already convinced the Colt is getting a variable optic and will be my "varmint" rifle.
I have read that chrome plating is not "corrosion proof", yet I've never had a chrome bore corrode. I know that one of the main benefits is that it greatly increases barrel life because it's many times harder than steel.
IIRC one of the reasons the military switched to a chromed bore on the original M16 was to prevent corrosion in the jungles of southeast Asia. So while it may not be foolproof, I take that to mean it's darn near corrosion proof.
Nothing is corrosion proof, given the right conditions. Your chrome bore is much more corrosion resistant than a bare bore.
Can't go wrong with either 6720 or 6920.
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