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How To Install a Lower Parts Kit in a Stripped AR-15 Lower – Build an AR Lower

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Table of Contents:
Magazine Release install – 2:19
Trigger Guard install – 5:46
Bolt Catch install – 6:48
Front Takedown pin install – 8:48
Trigger and Hammer install – 9:58
Selector Switch install – 13:51
Grip install – 14:56
Buffer Retainer install – 18:16
Buffer Tube install – 19:24
Rear TakeDown pin install – 21:04
Buffer Spring and Buffer install – 24:52

I have had this Wilson Combat stripped lower for about 4 months now and finally got around to building it. I purchased a Rock River lower parts kit to install because I have heard good things about the trigger. This video is a little long but I feel like all the info in the video is important. This is the second lower that Ive built, and it really isnt that hard to do. With a little mechanical inclination, the average person could get this done. I hope this video helps you guys out and maybe answers some questions on the difficulty of this process.

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49 COMMENTS

  1. I followed along and built my lower with zero problems.

    I wish you had done the build with s second camera operator. You got in the way of the parts a few times. But i'ze smurt nad figered it out! 🙂

  2. The part where he failed to show the pin and spring for the bolt release was when I had to move to a different video.

    Seriously, these videos need to take an extra 5 seconds to show a good close up of which pin and spring they are talking about. There's a shit ton of springs and pins in a lower kit, so simply saying "put the spring and pin in there" doesn't really help someone doing it for the first time which makes up 99% of the people watching this video.

  3. Sorry, but this is a pretty poor video. If you are a first time builder, I recommend you watch the assembly video at midwayusa.com or find it here (by Larry Potterfield). He does recommend some tools and equip that aren't essential for the one-time or occasional builder, but I believe it's a much better video. This one doesn't seem to be assembled correctly, as mentioned in previous comments, and I cringed when he hammered the trigger guard pin in with the lower unsupported…that's a good way to break off the "ears." Just my opinion folks; you're free to agree or disagree.

  4. 1. looks like the mag button is backwards. 2. the trigger reset springs big end goes in the trigger hole, looks like you have it backwards. 3. instead of using a punch, I just use channel lock pliers, to beating required. 4. the forward takedown pin detent, I just install the detent, then just push the pin over into the hole, no shim or box cutter required. 5. when I install the mag release button, I don't push the button in with a punch or anything, just pull the catch plate while you rotate, it pulls the button in without using a punch. Just a few suggestions, like you said, a million ways to do it.

  5. Decent video. Couple tips….install safety selector BEFORE trigger, or some triggers with a thicker baseplate you'll have to remove to install your selector. Secondly, ambidextROUS, not ambidextRIOUS.

  6. Worked perfect for me, I had my 300 blackout setup ready to go with this vid and was out shooting it the same day.  I liked that he did not use a vice and the perfect setup… I don't have a vice or a magazine holder… got the job done.

  7. I used this to put together my stripped lower. this was my first time even laying eyes on these parts. It was difficult seeing which part you were using. Especially not knowing the terminology. that's my main gripe. I made no mistakes aside from not getting the pin through the disconnector.

  8. Used your video to install my LPK into stripped lower receiver. Thanks for the video! This was my first build, also is my first AR. Had some issues following you (pins, detents, springs, etc.), so I had to rewind to see things that you apparently did off camera, but I got the jist. I've seen other videos as well and new my way around the parts kit, so that helped.. Thanks for the video!

  9. An ok video for a beginner, but when you say things like "the pin" or "the buffer" without showing the piece close up, it's not helpful because I don't know what piece you're talking about. A description would even be good.

  10. easier way to do that front taketown pin -.. just press down on the detent with the pin and twist it while pushing it into the lower. It worked so much better for me that using a razor/knife.

  11. you are not lubing anything in this video you should be lubing the detentes to make it easier for them to not get stuck. your safety switch is a great example of how a little lube would go a long way and make your weapon operate better.

  12. Good stuff – good orientation to building a lower.
    When installing pins, it's a good idea to place the far side of the work piece on a block of wood or other material.  That gives the worker a stable work surface, stops the pin when its flush on the other side and keeps the pin in the work piece if it's a loose fit.  
    Keep up the good work!

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