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Posted: 9/6/2014 8:06:10 PM EDT
| Hey there guys. I messed up BAD on an upper build I did. I attempted to build a MK 12 mod 1 upper by myself. I acquired all the parts I needed to build it. A stripped upper and all the parts that go with it, an 18" SPR profile barrel, the Ops Inc 12th model muzzle brake and collar, and the KAC free float rail. Now my first big screw up was with the rail itself. I didn't use any kind of grease or lubricant on the threads when I tightened it on to the upper, and as I was tightening it into place the DPMS armorer's wrench free float pins snapped and bent some of the free float pin holes inside of the barrel nut. Now, at first I thought the barrel nut was dead on straight (the free float wrench's pins just happened to snap right as I got it into place) but to further inspection I realized that the handguard was on a little crooked to the left. It was just a hair, but enough to bother the hell outta me. The second thing I messed up was the gas block. The gas block I bought for it is a badger ordnance mk12 profile gas block. It's supposed to be tightened on to the barrel with just an allen wrench, but it has now loosened up on me as well. The third thing I messed up was the muzzle brake. If you're not familiar with the Ops Inc 12th model muzzle brake, it has a collar that goes on before it that is tightened with another allen wrench. I tightened it real well, but as with the gas block it eventually came loose and now moves freely on the barrel. The muzzle brake is also a bit crooked. I feel like a total idiot and am not sure where to go with this. One of the free float pins that aligns the handguard is also seemingly stuck in one of the bent holes in the barrel nut. Could a gun smith deconstruct this and reconstruct it? Thanks guys. |
| Take it to a pro and have it looked over and find out just how much money in damages you cost yourself, on top of the armorer's hourly rate. most likely your FF HG is trashed, but it sounds like the rest is salvagable. Next time if you don't know what your doing, have someone who does do the work and watch/learn. Make sure you stick around and ask questions on what you did wrong, how to install such and such part, etc. It's a good way to learn. I had an experianced builder help me with my first complete build years ago, and I took notes and video'd the process so I had footage with notes to go off of when attempting a complete build for the first time. Youtube is your friend, you could have watched a video and saved yourself some money. Good luck with your build, get it done right and make sure you know wtf your doing so you don't break expensive parts anymore. |
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Thanks man. I think if a gunsmith uses some kind of grease or lube on the barrel nut threads that it will change the position it's on on the upper and different holes will line up that aren't bent. You didn't know that you are susposed to use moly grease or axel grease? Can it be completey disassembled and inspected, then possibly reassembled into a working condition or is the barrel nut and FF rail trashed/bent too much that it's noticable? |
| I also just completely disassembled the upper (minus taking the barrel off the upper as my only armorer's wrench has broken free float pins). I got the other free float pin out of the barrel nut, and I know I could get the barrel nut off if I had a free float wrench. I think I'm gonna buy another one and do it right this time. |
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Quoted:
I also just completely disassembled the upper (minus taking the barrel off the upper as my only armorer's wrench has broken free float pins). I got the other free float pin out of the barrel nut, and I know I could get the barrel nut off if I had a free float wrench. I think I'm gonna buy another one and do it right this time. I'm tryng to get a picture in my head of what your working with, which rail system is it? I'd be more help if I knew wtf your setup consisted of. |
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Quoted:
It's a KAC 12" free float rail That's a pretty tough rail, I'm thinking if nothing is busted or twisted badly, you should be ale to tear it down and reinstall with bettter results. You can go to KAC's website and they have installation instructions on their rail systems, I'd read up and look for a youtube installation video ......BTW is it the URX 4 rail? ETA: When on youtube Knight's Armament has their own Youtube channel for How to installs for their products it's called KACTV (Type KACTV "Your Rail" Installation) in Search. Or just go to their website like I previously said for instructions. Good Luck |
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Spartan: Remove that barrel nut and start over, this time with moly grease on the threads. The nut should have multiple places for the wrench to engage. If, after installation, the barrel is still not centered in the end of the FF handguard, then the front end of your upper receiver is not square. There are tools available to face it off slightly and remove the unevenness, or you could send it to a gunsmith and have that done, or even replace the receiver with one from a better quality maker.
I'm not familiar with the unusual gas block and muzzle brake you have. I presume they are specific to the Mark 12 configuration. Normal components clamp on or screw on tight as a drum with little fuss. I suggest you contact the makers involved for advice. Also, when installing AR parts for the first time, refer to the materials provided in the stickies here for guidance. That would have helped you avoid the greaseless barrel nut. - CW |
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