Posted: 12/10/2013 1:52:28 PM EDT
| Anyone here ever complete an 80% lower..? |
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"They say" you can complete one on a drill press, so I looked into it a little bit. To do it on a drill press pretty much requires some special dies or forms, which are expensive, and while 80% lowers are cheaper than 100%, there isn't that much advantage. My rough figures were that it would take 4-6 made just to break even, not counting any ones ruined in learning the process, so in my case they really wouldn't pan out, your results may vary of course. |
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Quoted:
"They say" you can complete one on a drill press, so I looked into it a little bit. To do it on a drill press pretty much requires some special dies or forms, which are expensive, and while 80% lowers are cheaper than 100%, there isn't that much advantage. My rough figures were that it would take 4-6 made just to break even, not counting any ones ruined in learning the process, so in my case they really wouldn't pan out, your results may vary of course. You have failed to account for the fun factor, plus the intangible off-paper bonus ("from the files, obtain form 4473"), and the incalculable value of having a gun you "made yourself", if only the last 20% 
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I thought this was a different take on 80% lowers -
80% polymer - if you believe in polymer ARs anyway. The material to be removed is a white plastic, so the piece doesn't run afoul of ATF rules on locating holes. Looks like a pretty good simplified way of making a lower without needing fixtures. I've heard of a couple of guys that botched them though. I'm half interested in trying one out, but you know how that goes, once you got a spare lower, it starts turning into a complete rifle. |
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I made one without a jig. The 80% I used a factory lower by laying them both on a flat surface upside down. I squared up the two lowers and ran a starter punch through the holes on the factory lower to mark the FCG holes on the 80% lower. Worked great.
I did start with an older 80% lower that had the FCG area milled out but was undersized. Instead of machining out the FCG pocket to spec, I shaved a few thousandths off the hammer and trigger to get them to fit. Only issue I had was getting the buffer tube hole drilled square. Mine is off just enough that the bolt drags slightly when firing. Not enough to affect firing but you can hear it drag. My buffer tube threads got boogered up when I tried to fix it. I taped it at an angle and tried to straighten the threads. Now I need to wled the tobue to the lower for it to work properly. Not a big deal on a trunk gun. The new 80% lower require to FCG pocket to be milled and a jig is necessary. |
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here's a pretty good deal on GB, but be advised they don't appear made by the "usual suspects" i.e. Cerro Forge (keyhole mark) etc, also they don't state whether forged or cast, they are A380 aluminum,(not 7075 , or 6061) , and the contours are all wrong, too sharp, and flared mag wells? not USGI by a long shot.
most of the 80's in the market get their raw forgings from the same foundry's as the completed lowers, thats why they're all about the same price. i would imagine it costs the same to stop the CNC before finished as letting it go all the way. coupled with lower numbers, that's why 80's are at least as expensive as completed lowers. except for theese guys, not suprised if they were produced in China, Frankensteen or Oogaboogastan.. it's a gamble for sure. |
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Quoted:
here's a pretty good deal on GB, but be advised they don't appear made by the "usual suspects" There's a thread about them out in the mainline forum http://www.ar15.com/forums/t_3_118/622337_Vision_Armory.html The first two images on the Gunbroker page are computer generated but some of the photos around the web show that they are for sure castings. They say they only have 20,000 so we should hurry up and order! |