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  1. #1
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    1st Build Shenannigans

    ok so I finally sold my 1st AR, a Rock River Arms, to a friend to further finance the build I have been collecting parts for. The RRA was in pieces, and I had to put it back together. So, on top of already being a bit nervous about putting a gun back together that I had already collected money for (and spent said money) and it being my first time fully assembling an AR, I had to do this at work with about 6 people and an 11 year old watching my every move. Two rookie mistakes followed:

    1. Installed and fully torqued down the buffer tube before realizing I had not installed the rear take down pin and spring.

    2. Upon loosening up the buffer tube to fix issue #1, I proceeded to jettison my buffer retaining spring and pin into the nether. Which I had to replace with the parts I was using for my personal build. Doh!

    Good news is, even though we haven't fired it, the RRA seems to be functioning fine, with the FSB lined up well and it appears as if the bcg and gas tube aren't having any friction or contact issues. Headspace is ok according to the Brownell's no-go gauge. This at least gives me a little confidence for my personal weapon, even though I will be tackling a piston system.

  2. #2
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    Just remember to look kool in front of chicks as you put it back together. That was one of the things I learned in the Colt Armorer School. LOL.

  3. #3
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    Common build mistakes to avoid:

    Improper torque on the barrel nut. Anything above35 but not in access of 80 lbs is a good rule of thumb.
    Don't locktight the buffer tube (like RRA does). When you have to take it off, you will most likely strip the indexing thread.
    The FAT end of the disconnector spring faces down.

    Good luck with the build and have fun.

  4. #4
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    In an attempt to embarrass myself as much as possible on a forum full of experts, while attempting to figure out what the hell I am doing in the process, I wanted to keep you guys abreast of the mistakes I am making and what I am learning while trying to get my build together.

    First of all, the Bushmaster combination barrel wrench/buffer tube wrench is, in my opinion, crap. It has some strange finish that neither myself or any of my friends can pinpoint, but rest assured that this finish will start flaking off and causes the wrench to slip easily off the barrel nut just when you are under pressure. Also, the cutouts for turning the two different sizes of flash suppressors are sized very loosely, and when you add in that flaky finish, it resulted in some very ugly scarring on my beautiful new Rainier XTC. Not happy about that at all.

    I am also learning that using a 3/8" torque wrench with a 1/2" adaptor to fit in the barrel wrench is not a good idea. Especially on this Bushmaster tool, which again seems to have loose tolerances. Now, I can imagine that just using the adaptor causes some play and some undesirable leverage issues, which may have somewhat contributed to the wrench constantly slipping/stripping off the barrel nut, but without that cruddy finish on the tool, I think I could have made it work. But as it stands, I had all kinds of trouble putting my barrel and upper together. I was attempting to initially torque the nut to 50 foot pounds and then tighten to line up the barrel nut, but I swear I could not get the barrel nut to turn once it hit that 50 lbs without the wrench stripping off the nut. It doesn't look like too much damage was done to anything, but I still may buy another barrel nut just to be safe. I think I am most definitely going to buy a different barrel wrench, and I have my eye on one from Brownells that is not open-ended, and must be slipped all the way over the end of the barrel to work. It has teeth that surround the nut all the way around instead of just the half-circle or 3-prong type on the bushy. It also has holes for both 3/8 and 1/2" torque wrenches on the same tool. If anyone has any advice or idea for a better tool, I would love to hear it.

    As for the flash suppressor, can someone advise me on the torque necessary to index the XTC? First, should the crush washer's conical end be facing the barrel side or the flash suppressor side? When you screw down the suppressor just to where it makes contact with the crush washer, about how many full turns should be necessary to get it to the proper torque? It seemed like it took maybe 1/2 a turn to line it up straight on the first pass, but I thought it might require more, so I turned it another full turn after that. I removed it because it took a buttload of strength to get it to that full turn and it looked like the crush washer was pushed way out, so I took it off to make sure I did not damage the barrel. It doesn't look like the threads are damaged, and the suppressor screws all the way down with no problem, but I now need another crush washer and I don't want to waste another one.

    Any help is greatly appreciated guys, and I am sorry if I am posting in the wrong area. Moderators can feel free to move it if necessary.

    I am in the finishing stages of this project, and I am getting super-frustrated. I am just about ready to take $1700 in parts and $500 in tools and take it all to the nearest river for one of those "tragic boating accidents" that befall so many firearms.

  5. #5
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    Once you get to about 30 lbs, you will need to align to the next hole. The problem is that many barrel nuts & uppers shouldn't be used together. When we build uppers here, we go through several barrel nuts to find one that will be just right. Unless you are using a DD Lite rail or something else that doesn't need the barrel nut indexed, you will most likely need more than one barrel nut to get the proper fit. The best barrel wrench I've found for milspec barrel nuts is the Olympic Arms multi-too.

    As far as using a crush washer, you can actually crush your washer 360 degrees you just align it with the mountain logo on top and then you are done. I don't recommend going over 360 degrees. As far as marring, you can use 2 thin card board pieces or construction paper pieces in between the wrench and the comp or use WD40 on the comp which also helps with the marring.

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