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Posted: 1/13/2010 3:55:34 PM EDT
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Hey Guys -
So I am in the process of SBRing my Colt 6920 and waiting for my tax stamp to arrive. My original plan was to purchase a 6921 upper from Gunbroker once I got my stamp and selling my 6920 upper. In addition to wanting a true 14.5" upper, I wanted to build a kit similiar to that seen on some of the navy seals weapon kits where they also have a Mk18 CQBR. Originally I was going to purchase an LMT 10.5" upper for this purpose, but since I have used my current 6920 upper a fair bit I was thinking that instead of selling it, I woul send it off to ADCO to have the barrel chopped to 10.3" and have the gas port opened up to the Mk18 specs. My question is this; does anyone see a problem with doing something like this? Would it be better to just try and sell the 6920 and purchase the LMT? Thanks in advance for your help! |
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Hey Guys - So I am in the process of SBRing my Colt 6920 and waiting for my tax stamp to arrive. My original plan was to purchase a 6921 upper from Gunbroker once I got my stamp and selling my 6920 upper. In addition to wanting a true 14.5" upper, I wanted to build a kit similiar to that seen on some of the navy seals weapon kits where they also have a Mk18 CQBR. Originally I was going to purchase an LMT 10.5" upper for this purpose, but since I have used my current 6920 upper a fair bit I was thinking that instead of selling it, I woul send it off to ADCO to have the barrel chopped to 10.3" and have the gas port opened up to the Mk18 specs. My question is this; does anyone see a problem with doing something like this? Would it be better to just try and sell the 6920 and purchase the LMT? Thanks in advance for your help! I would keep the 6920 upper and get the LMT 10.5 from Bravo co.Then when ya get the stamp ya could swap uppers around etc. 
looks like they are out of stock right now but keep checking they get more in... http://www.bravocompanyusa.com/LMT-10-5-M4-Carbine-Upper-Receiver-Group-p/lmt%2010.5%20urg.htm |
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Thanks for the feedback guys. Are there any drawbacks to cutting the 6920 down to 10.3" that lead you to beleive it would be better just to buy a LMT 10.5"? I'm not opposed to it, I'm just curious if there are drawbacks that I am not aware of. Personally I believe you would be much better off having ADCO chop your 6920 upper then buying LMT. 1. You can have the 6920 upper chopped to what ever length you want, 10, 10.3, 10.5, 11, 11.5, etc. 2. If you have a good shop like ADCO do the work, the newly rethreaded barrel and recrowned may be more accurate. 3. LMT uses a medium contour, the 6920 is light contour under the handguards, this will mean a lighter handier firearm. 4. Should you run a suppressed, a precision rethreaded upper will have negligible to zero POI shift vs how ever much POI shift you will have with a milspec threaded upper. For example, my LMT 10.5 had a 10 MOA POI shift when suppressed. My ADCO chopped upper have no noticable POI shift. 5. The gas port can be opened to what ever is ideal for your rifle. Now there are down sides: If you pick a bad shop, they can screw up your upper badly. Because the chrome lining is cut, and the barrel recrowned, if you run suppressed, muzzle erosion may be faster. However I have never heard of any having any issues with this. If you send your upper to ADCO, you may have to wait TWO WHOLE WEEKS before you get your upper back. I mean, thats just unbearable. |
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Thanks for the feedback.
That is what I was thinking would be the benefits of doing it this way. I just wanted to make sure there wasn't a negative reason not to do this that I wasn't aware of. Like I said originally, I've put a decent amount of rounds through my 6920 upper and thought that it would be more economical just to have it chopped into a MK18 upper instead of trying to sell it and then buying a LMT 10.5" upper, plus bolt and bolt carrier etc... |
| I agree with postal but with the addition of one other small point. If you get the 6921 and have your barrel chopped, it would be how a large portion of the SEAL guns are made. That is a factory 14.5" and a 10.5" cut down standard bbl. Just one more point to consider. ––ST |
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A little late, but I would buy the 14.5 and cut your current barrel to your liking. Plus, you would still have all Colt parts if that matters to you.
I had my 6920 barrel cut to 12.5 by a fellow arfcommer. I've had a LMT 10.5 upper before and the contour under the handguards makes a small, but noticeable difference in weight. I would say my 12.5 barrel has the same weight feeling as the LMT 10.5. If you cut the 6920 barrel down, it would be lighter (I like lighter). Since everybody likes pics... The cut barrel shoots more precisely and has less POI shift with the suppressor. 
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Kinda sorta what you're trying to do. Thought I'd give you something to look forward to.
The top rifle is a 14.5" LMT barrel with a KAC RAS 2, LT QD low aimpoint mount, Aimpoint ML2, BCM CH, MP BUIS on a registered FA lower. The bottom rifle is my rendition of a MK 18. LMT 10.3" with KAC BUIS, Aimpoint, Geiselle trigger, etc 
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Wow...I didn't realize there had been this many more responses to my thread. Thanks for all the additional information guys! Quick question, how much did you have ADCO open the gas port when you had the barrel cut down to 10.3" to ensure proper operation? Frankly, I had an email conversation with ADCO and told them I was looking to have it cut to 10.3", as I was building a Mk18 clone. I let them run with it from there, and they said they would handle the gas port modification. |
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Kinda sorta what you're trying to do. Thought I'd give you something to look forward to. The top rifle is a 14.5" LMT barrel with a KAC RAS 2, LT QD low aimpoint mount, Aimpoint ML2, BCM CH, MP BUIS on a registered FA lower. The bottom rifle is my rendition of a MK 18. LMT 10.3" with KAC BUIS, Aimpoint, Geiselle trigger, etc http://i293.photobucket.com/albums/mm77/hardgear/ar15uploads/P1010235.jpg Very nice. What sling setup is that? |
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Kinda sorta what you're trying to do. Thought I'd give you something to look forward to. The top rifle is a 14.5" LMT barrel with a KAC RAS 2, LT QD low aimpoint mount, Aimpoint ML2, BCM CH, MP BUIS on a registered FA lower. The bottom rifle is my rendition of a MK 18. LMT 10.3" with KAC BUIS, Aimpoint, Geiselle trigger, etc http://i293.photobucket.com/albums/mm77/hardgear/ar15uploads/P1010235.jpg Very nice. What sling setup is that? Thanks. It's a Vtac 2 point sling with MI QD swivels. The Sopmod stock and MRP have built in QD bushings |
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This is what I had on hand, and postal firmed up my reasoning behind it. http://i255.photobucket.com/albums/hh126/bklynirish/BushmasterM4geryDoublestarA4gery004.jpg This is the beginning of Mk 18 Mod 0 clone. Barrel cut down by ADCO, now waiting on the paperwork. http://i255.photobucket.com/albums/hh126/bklynirish/DSCN1250.jpg if you already have the upper why are you still waiting on the paperwork? isnt that concidered contructive intent? |
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This is what I had on hand, and postal firmed up my reasoning behind it. http://i255.photobucket.com/albums/hh126/bklynirish/BushmasterM4geryDoublestarA4gery004.jpg This is the beginning of Mk 18 Mod 0 clone. Barrel cut down by ADCO, now waiting on the paperwork. http://i255.photobucket.com/albums/hh126/bklynirish/DSCN1250.jpg if you already have the upper why are you still waiting on the paperwork? isnt that concidered contructive intent? Read towards the bottom of this thread. |
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This is what I had on hand, and postal firmed up my reasoning behind it. http://i255.photobucket.com/albums/hh126/bklynirish/BushmasterM4geryDoublestarA4gery004.jpg This is the beginning of Mk 18 Mod 0 clone. Barrel cut down by ADCO, now waiting on the paperwork. http://i255.photobucket.com/albums/hh126/bklynirish/DSCN1250.jpg if you already have the upper why are you still waiting on the paperwork? isnt that concidered contructive intent? Read towards the bottom of this thread. Hey youre the one that stated you INTEND to use it on a rifle lower but dont have your paperwork back yet. If its not in your possession yet thats fine and dandy but if you have another ar15 laying around wouldnt that fit the defenition? Dont get me wrong im not tryin to tell ya what you can and cant do i was just trying to make sure you didnt burn yourself. |
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Tony_k has already said stop the constructive intent nonsense. If you want to learn about ATF guidelines there's a place to do that, nobody appointed anyone Internet BATFE hall-monitors so youre saying the class 3 firearms forum isnt the place to learn about atf guidlines? 
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Tony_k has already said stop the constructive intent nonsense. If you want to learn about ATF guidelines there's a place to do that, nobody appointed anyone Internet BATFE hall-monitors so youre saying the class 3 firearms forum isnt the place to learn about atf guidlines? Correct. This is not the place. This forum is for technical discussions of buying, building and maintaining NFA firearms themselves. It is a nuts-and-bolts place. We have a separate forum –– General Class 3 Forum –– which covers legal discussions as well as application procedures, ATF requirements and regulations, etc. |
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Tony_k has already said stop the constructive intent nonsense. If you want to learn about ATF guidelines there's a place to do that, nobody appointed anyone Internet BATFE hall-monitors so youre saying the class 3 firearms forum isnt the place to learn about atf guidlines? Correct. This is not the place. This forum is for technical discussions of buying, building and maintaining NFA firearms themselves. It is a nuts-and-bolts place. We have a separate forum –– General Class 3 Forum –– which covers legal discussions as well as application procedures, ATF requirements and regulations, etc. funny i guess that didnt apply in this thread then http://www.ar15.com/forums/topic.html?b=6&f=22&t=303000 or this one http://www.ar15.com/forums/topic.html?b=6&f=22&t=303165 but i guess youre the mod so you get to decide what questions youll allow and where. if you look im sure youll find plenty of cases where you not only allowed but answered legal questions in this forum |
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brokeforguns, thank you for pointing out the first example. I moved it to the correct forum.
People post questions in the wrong forums all the time. When I find them, I move them to the correct forums. But this is not a full-time job for me, nor even part-time. So yes, I often miss incorrectly located posts. Sometimes, threads start out in one area and develop into another before I get a chance to move them. That is what happened in the second of the threads you linked –– it ended up as much a technical thread as a legal one, so I left it where it is. The OP in this thread was technical. And I would like to keep it that way, despite the efforts of some to take it off-topic and into the realm of another forum. Thus, no discussion of "constructive possession" here. Let's keep it technically on-topic. Thank you for your cooperation. |
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