I got in on the Pre-Production buy on these in this thread :https://www.m4carbine.net/showthread.php?t=14838.The deal from start to finish went smooth. Today my lower parts kit came in so it was time to build up my first lower.
I used the guide from TOS and followed the instructions. I went at this with just a hammer, screw driver, a 1/16" punch, a drill bit, a chuck key from my drill, and some hex wrenches. The parts kit was CMT/Stag.
Everything went well aside from the bolt catch assembly. I had two problems here. First, I misinterpreted the diagram and put the roll pin in from the wrong side. This resulted in me dinging the receiver with a slip of the drill bit I was using as a punch even though I taped off the area to prevent just such a thing. Had I gone in from the other way, I would have been golden. Lesson learned.
While I would have rather not have dinged it, I'm not upset over the mark other than because it was a bone head move that caused it. It's gonna get marked up from use anyways.
The second issue I had with the bolt catch was that it wouldn't hold the bolt open when function checking it. Comparing it to my Bushmaster bolt catch, it had much more tension and the mag followers wouldn't activate it. They are very lightly used Pmags so I know the mag springs would be good to go. So I swapped the bolt catch from my Bushie to my CD lower and the bolt hold open now worked. I installed the CMT bolt catch in my Bushie and it works fine there.
Since I used some improvised tools to put this together, I am sure some of you are wondering just what the hell I used the chuck key from drill for. Well it turns out that the chuck key handle is the exact same diameter as the front pivot pin. As you all know and I found out, the pivot pin detent can be quite a challenge to put in. My first attempt using a hex wrench thru the pivot pin holes didn't work so well and resulted in a launched detent and spring. Fortunately I was able to find both. I then got a sandwich baggy to put over the lower and saw the chuck key sitting there. lo and behold, it was a perfect fit. So I slid it in and used it to hold down the detent. Then I pushed the pivot pin across to take the key's place and it worked perfectly.
I do have another issue but it is primarily cosmetic. The pistol grip is canted to the left. I'm not sure if the grip is off or the lower. The lower does have some sloppy machining around the trigger area as indicated in this picture:
Bushmaster on left, CD on right.
There is a ridge that runs along the center and it is uneven in height and where you mount the trigger guard with the roll pin, if you look down between the ears, it is very noticeable and quite jagged looking. I will get pictures of it late when I have my camera available. This does not interfere with the function, however. My Bushmaster lower also has a slight ridge but it is much less noticeable and and uniform. I am chalking this up to being a preproduction lower. For the price I paid, it is fine since it functions fine. If this was a production unit and I paid full price, I wouldn't be as happy.
There is a lot the satisfaction in doing it yourself and I also learned a lot. It'll be more satisfying when I get a chance to shoot it for the first time.
Next up, building my own upper.
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Originally Posted by Lagadelphia
5.45x39 is cheap....and so am I :0
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