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Posted: 3/30/2009 6:32:29 PM EDT
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With the shortage of AR lowers and Obama concerns, I thought I would try completing an 80% lower.
In the interest of full disclosure, I should mention that Yellow Logic just recently started offering these billet 80% lowers. After conversing with the owner (nice guy) I agreed to document my build in exchange for the lower. Other than that, I have no connection with Yellow Logic, or their excellent looking AR lower. 
 
These lowers are machined from 7075 billet and then bead blasted after machining for a nice satin finish. It has the look of pewter. Operations necessary for completion of the lower include: •Drill and tap grip screw hole •Drill hole for buffer retainer detent and selector detent •Drill for selector, hammer pin and trigger pin •Drill for bolt catch pivot pin and front detent vent •Mill out pocket for rear take-down lug •Mill out pocket for Fire Control Group •Mill trigger slot A quick trial fit of the mag latch, bolt catch, buffer tube and stock show perfect fit. All machining will be done on my Enco 45. 
I am not a professional machinist and this mill/drill is strictly manual. I don't even have DRO, so everything is done with the handwheels on the machine So here goes: 
I clamped it in the vise using spacer blocks on each side above the rear portion of the trigger guard to even it with the mag well. Then indicated the top plane for parallel. 
Then indicated off the side of the lower to align with the X axis. All is good to go. Took me about 30 mins. to do this, plus the time to make the spacer blocks. 
Using ATF for lube, I drilled a relief hole to depth since my endmill is not centercutting. Then I used this long reach 3/8 endmill (cobalt). I took it down in increments of .030. I probably could have taken deeper cuts, but I didn't want to take the chance. I milled dry with air at about 15psi. This took two hours. Remember that I do not have DRO and am doing this with the handwheels. If you look close, you can see why I wasn't real worried about the very light machine marks on the outside of the lower. The ones I left inside are quite a bit more noticeable. You can also see that my first pass was a little wide as the Y backlash caught me napping. :( 
Upper and lower match up VERY tight, but not so you can't push the pins in with your thumb. 
I think she will be very nice when completed. Finished milling out the Fire Control Group pocket and nearly had a disaster. 
Milled out the deep portion using an extended length 3/8" endmill taking about .040 per pass. It was slow going, but worked fine. Had to kick the air up to about 35psi to keep the chips clear. This took about 3 hours. 
This pic was taken after drilling and tapping the grip screw hole, but here you can see my "close call." I was milling into the rear shelf and feeding too fast. The helix of the end mill side cutting into the shelf was enough to slowly pull the the cutter down out of the collet which resulted in cutting down into the floor about .010". Fortunately, I didn't cut through and that area is well supported. So, other than the fact that I know it is in there, it has no effect on the lower. 
Here's my set-up for drilling the grip screw hole. First, I installed the grip and then marked the hole with a pencil. Drilling was with ATF for lube and I backed the drill out frequently to keep the chips clear.  
Tapping that deep hole was fun. I used Tru-Tap oil, went slow and backed it out frequently again to keep the chips clear. The grip screw fits fine. Drilling and tapping took about 30 mins.  
I used an extra long reach center cutting endmill to drill the hole for the buffer detent and spring. I forgot to take a pic of my setup, but I hung the back of the lower out the side of the vise to drop it down on a block with shims to get the 6°(+/-) angle needed on the hole. It took another 20mins. to setup and drill and worked out fine. 
Had to take a minute to install the grip and buffer assembly with an upper to check fit and function. Hand cycling the buffer shows that the tower alignment is perfect. This baby is smooth. Next, I cut the hole in the bottom for the trigger to pass through to the guard. I forgot to take pics, but I set it in the vise the same as I did for the FCG pocket and used an extra long ¼” endmill for the job. Took about another 20mins. 
Next, I indicated front to back and top to bottom to make sure it was level so I could drill the FCG holes all the way through from one side. Be sure that the underside of the receiver is well supported to prevent it from shifting during drilling. You can also see the hole for the trigger to drop down into the guard. 
After consulting the drawings, I used a centerfinder to index off the front pivot pin. Then, just to check my setup, I handwheeled to the rear pivot pin and found that we were dead on. So, I first drilled a pilot hole then drilled the selector to size. Drilled through to the other side and then test fitted the Selector. It fits snug and flat against the side of the lower so I should be good. 
Selector is drilled and hammer and trigger pin holes are center-pointed. This took about 30mins. because I checked it twice.  
Drilled the trigger pin and hammer pin holes through both sides using 35psi air and no lube. Took about 10mins. 
Fire Control Group installed. Everything fits very nicely. 
Everything is where it is supposed to be and a quick function check shows SAFE is safe and FIRE releases the hammer and then the disconnector catches properly upon return. Life is good! 
Underside shows that trigger fits well in the slot. Only thing left to do is drill the selector detent hole and the bolt catch pin hole (oh and the front detent vent hole). None of these are critical so I don't expect any issues. |
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makes me want a milling machine.... very nice. I said that for nearly 20 years. Last year, I decided that the equipment was as cheap as it was going to get and just bought it. I am REALLY glad I did because now I'm making chips instead of just wishing I could. |
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Dude seriously? 265 for an 80% lower?
Shit Ill sell you a 100% lower for that.......not machined at my house either. Im sure its a nice part but there is no way in hell its 265 nice. I have all the CAD CAM for both 15s and 10s and I still choose not to build those things because they are so cheaply had elsewhere. If it was 150 Id almost bite for someone to snag them just being that they dont need FFL paper work and all that crap but not at 265 |
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Dude seriously? 265 for an 80% lower? Shit Ill sell you a 100% lower for that.......not machined at my house either. Im sure its a nice part but there is no way in hell its 265 nice. I have all the CAD CAM for both 15s and 10s and I still choose not to build those things because they are so cheaply had elsewhere. If it was 150 Id almost bite for someone to snag them just being that they dont need FFL paper work and all that crap but not at 265 The lower work is nice but I'd have to agree. I was thinking about checking out this company until $265 for an 80% lower came up. To steep for my taste. |
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Dude seriously? 265 for an 80% lower? Shit Ill sell you a 100% lower for that.......not machined at my house either. Im sure its a nice part but there is no way in hell its 265 nice. I have all the CAD CAM for both 15s and 10s and I still choose not to build those things because they are so cheaply had elsewhere. If it was 150 Id almost bite for someone to snag them just being that they dont need FFL paper work and all that crap but not at 265 This too (price) has stopped me from attempting one of these lowers. I've also looked into some of the bronze blanks just for giggles. I've looked at the titaniums ones also but have had too many tell me not to go this route, apparently it is hard to work with. I have a friend who is a machinist for an aircraft parts company and he has a nice mill at his home. His work is beautiful and he indicated that he would walk me through every step just so I could say I did this. I have the blue prints and he said, "seriously this is no big deal with my equipment, just a Saturday afternoon job." I just can't justify the price even when considering the higher level of satisfaction one would receive when doing a build like this. As far as the registered part issue goes. I still see many lowers for sale locally where the seller requires no paper trail for sub $200. Price excluded it's great to see someone doing this. I admire your determination. |
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Like other firearms parts, 80% lowers are not easy to locate right now.
These are BILLET lowers and therefore cost more than castings or forgings. Billet lowers are not for everybody. Forged is good enough for most. Many are happy with cast. Some don't even know the difference. You may be able to sell me a lower that wasn't made in your garage, but you can't sell me one that was made in MY garage. However, finishing the machine work also is not for everybody. As you pointed out, it certainly isn't cost effective. In my profession, I charge $100/hr for my work, so the time I spent on this project had a much higher cost point than the receiver alone. But I didn't do it to save money. I did it because I enjoyed it. Anybody can assemble an AR, but I wanted to take it a step further. Now I want to continue to do more of the work on my own....just because. 
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Time to drill the selector detent hole so I can finish this build.
 
I don't care for enlarging an existing hole with a drill bit (except pilot holes) so I drilled the 5/32" portion of the selector detent hole first. Then, without moving the setup, I drilled the rest of the way with the 1/8". A quick check shows the detent fits, but not too deep. Took about 10mins. 
Now it was time to set up to drill the bolt catch pin hole. I had to get out the angle plate for that one. Since I'm not using any jigs for this build, I had to center punch the spot quite deep to keep that long extension drill from walking.  
Using cutting oil and air, it drilled through just fine. Now it's time to assemble!  
Finished!! Now I just need to take it out and "fire for effect." This was a fun build and I am very pleased with the results. |
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Just a quick heads up to 80% buyers...
Since Oct/Nov 2008 to current... BATFE states that "A blank, having any fire-control pivot pin holes drilled or indexed, or any portion of the fire-control cavity milled will be classified as a firearm per 18 U.S.C. 921 (a)(3)." It's their underlining, not mine. That is a quote directly from my letter from the BATFE dated March 20, 2009. With everything that's going on, be safe you guys. If someone is selling you anything that has what's quoted above... run, don't walk away. I know they are out there. I see them on gunbroker.com and at least one web site out there for sale. To be clear, the BATFE is saying these features makes it a firearm. For someone (no, not Jusbo47 but sellers of these parts) to knowingly advertise, publish pictures of or sell will get your backside in a ringer. How long do you think it will be before someone (seller of) is visited? Enough said. In an effort to be fair, this is a build from one of my lowers. I have gone to great lengths to be legal and produce a quality product. As mentioned above, the fire control group was solid as directed by BATFE. |
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I got both of mine last year, before the BATF date , just took me a while to get to them, both are keepers, one for me and one for anyone who is shooting with me to use also.
I sold my other 3 rifles that had registered lowers. I do have one forging that needs the deck milled and the magwell cut out,also the front lug and trigger guard area would be a plus also. I have a jig to do the holes and to help with the FCG well. |
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I was amazed at how many people were into finishing their own. It's one of those things. My wife looks at me and does the silent "whatever" look and tells me of some task she wants me to do.
I enjoy it and it's an added part of the experience. Have you checked out homegunsmith.com forums? Some of their projects are truly from 0%. Ok Jusbo... how did you finish your lowers? Anodize, one of the spray on finishes like DuraCoat or something else? |
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Like other firearms parts, 80% lowers are not easy to locate right now. These are BILLET lowers and therefore cost more than castings or forgings. Billet lowers are not for everybody. Forged is good enough for most. Many are happy with cast. Some don't even know the difference. You may be able to sell me a lower that wasn't made in your garage, but you can't sell me one that was made in MY garage. However, finishing the machine work also is not for everybody. As you pointed out, it certainly isn't cost effective. In my profession, I charge $100/hr for my work, so the time I spent on this project had a much higher cost point than the receiver alone. But I didn't do it to save money. I did it because I enjoyed it. Anybody can assemble an AR, but I wanted to take it a step further. Now I want to continue to do more of the work on my own....just because. While believe me, I can admire you finishing up one, like others have said its not if at all, difficult to do with anything more than a mill-drill. With basic hands on knowledge of how to measure everything up you should be able to fudge your way thru it. No I cant sell you one that was made in your garage........but at that price Id have gnawed one out of aluminum with my teeth (insert sarcasm I love the idea of keeping my teeth) and the reply wasnt that youre incapable or even stupid for doing it. I just dont believe the price is reasonable. I have extensive knowledge of machining and a billet lower is not any better than a forged one. In fact, a billet lower is quite possibly heavier than a forged one with a near identicle level of durability. The poster who mentioned titanium? Its a good to go kind of deal but it actually outweighs aluminum cubic inch for cubic inch on most alloys if not all. The elemental problem with titanium is that its highly prone to galvanic corrosion and needs to have generous relief cuts on all angles respective to size though. The problem encountered with a cast lower is obviously the locator pin holes wearing out. This is the point of damage on an AR that is of concern seeing as it is required to absorb and distribute the firing load between the upper and the lower. Cast would cause problems if not properly bushed with something like bronze or similiar harness. I give applause to you bro, I really do. I just think that whomever is behind that 80% lower on that price is ripping people off. |
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Hey, it's not for everybody. The production costs are pretty high and by the time a finished product is shipped, there's a lot that eats into anything you could have made.
You're looking at batch #1. I broke even on it. Hard to rip someone off if I broke even. No one has complained about the price that actually bought one and I sold out in 22 days. When I started, I insisted that it be highest quality materials and machined to exacting specs. Every 10th piece is quality checked. The machine set up is spot on and the EDM of the mag well is perfect. Sure, you can buy illegal 80% elsewhere for less but they are dented and dinged, the mag well is not correct and look like they were cast in your neighbor's back yard. Hey, it's cool. This is not a part or project for everybody. You sound like you understand the process and what's involved. I've sent you a IM. |
I'm sure breaking even was pretty fun to do though. 
Yah it's hard to make money on it if you have external sources to make your stuff. You need to have either a one stop shop to do both the CNC milling and the EDM or have your own equipment. Also it would help to do a large run rather than a limit run. I'm looking at the one in front of me and over all I have to say the design looks really good. One side has flawless finish, the other has some minor tooling blemishes that can be removed with a little sanding. Considering this was your first try at this.. it's really remarkable. The style in itself is very unique which drove me to purchase one. I look forward to your next production run. Hope you can get a price break for producing it. I'm sure it'll be better then the first prototype run. Be sure to show me some pictures. 
BTW the link to TheOtherChris's documented work on this is at: link |
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I finished my first one with Alumihyde ll in Pakerizing Gray.
The second just got media blasted today , it worked the side down to a slab side configuration and just used Krylon for now since the funds are in short suppy for now. I would like to have them anodized but since the probablity of the holes coming out oversized does not thrill me one bit. Krylon is cheap and I dont mind touching it up later if needed. |
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I finished my first one with Alumihyde ll in Pakerizing Gray. The second just got media blasted today , it worked the side down to a slab side configuration and just used Krylon for now since the funds are in short suppy for now. I would like to have them anodized but since the probablity of the holes coming out oversized does not thrill me one bit. Krylon is cheap and I dont mind touching it up later if needed. Any pictures?
What do you mean by the holes coming out oversized when you were talking about anodizing? I would think it would be undersized if your tolerance of the holes were exact size and then you anodized. |
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Hey, it's not for everybody. The production costs are pretty high and by the time a finished product is shipped, there's a lot that eats into anything you could have made. You're looking at batch #1. I broke even on it. Hard to rip someone off if I broke even. No one has complained about the price that actually bought one and I sold out in 22 days. When I started, I insisted that it be highest quality materials and machined to exacting specs. Every 10th piece is quality checked. The machine set up is spot on and the EDM of the mag well is perfect. Sure, you can buy illegal 80% elsewhere for less but they are dented and dinged, the mag well is not correct and look like they were cast in your neighbor's back yard. Hey, it's cool. This is not a part or project for everybody. You sound like you understand the process and what's involved. I've sent you a IM. just ignore that guy he has no clue when you build less then 50 & someone like stag builds 1,000's who will be cheaper? I bought 3 cmmg's a few months ago for $145 ea I can still buy them for that, instead I bought one of these in 60% for $225 and jigs were another $99.95 & $124.95 at cnc does it sound like I did it to save $ ? price is not the end all of everything 
I choose to spend my hard earned$ any way I see fit, you put out a great product. if price were too high, they would not sell. |
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Hey can I toss in my $.02 that will save you a bunch of $$$$$$. First, I am saying this because obviously you have the machine and the knowledge and skill to do this kind of work. For $27 you can call up to superior and buy 0% forgings. That is the way we do all of ours. I have done 8 lowers from 0% forgings. I mean look, you're already doing A LOT of cutting on the fire control wells. You seem VERY able to do precise locating, and the mag well is actually easier to machine than the FCG well. For the $265 for one 80% you could have like 6 -7 lower forgings from superior INCLUDING the shipping. I mean just my opinion, but if you have the skill and machinery, why not start from scratch and save some serious $$$$. If you have any questions about the 0% just email or make a post. There are plenty of people starting from scratch that would love to help!
Dan |
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psst... Don't tell anyone but there's going to be a tax day Tea Party sale and I'm going to lower the price....
I thought about the forgings. I have 3 or 4 untouched. They have surface dents and dings and would not allow me to customized the exterior. Sure, I could still do the 9mm versions I'm starting next week but I wanted tough and durable and not dependent on someone else for the blank. The first batch was priced at $255 and almost all sold in the sale I had at a much lower price. I am working on price control and lowering the price. |
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I could have sworn I posted this up.. but I don't see it.. any case..
These things are not crazy expensive if you look at what needs to be done to them, the quantity of the build, and quality of the material. His lower is very unique and I think more desirable than the standard looking lower. I would put this one next to my Magpul MPLA once I'm done building it. I believe he really did put some thought and time into it and it was a pretty successful first try. As for the surface scratches he mentions, they are very minor and come out easily. I know because i have one in front of me. |
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Hey can I toss in my $.02 that will save you a bunch of $$$$$$. First, I am saying this because obviously you have the machine and the knowledge and skill to do this kind of work. For $27 you can call up to superior and buy 0% forgings. That is the way we do all of ours. I have done 8 lowers from 0% forgings. I mean look, you're already doing A LOT of cutting on the fire control wells. You seem VERY able to do precise locating, and the mag well is actually easier to machine than the FCG well. For the $265 for one 80% you could have like 6 -7 lower forgings from superior INCLUDING the shipping. I mean just my opinion, but if you have the skill and machinery, why not start from scratch and save some serious $$$$. If you have any questions about the 0% just email or make a post. There are plenty of people starting from scratch that would love to help! Dan Funny you should mention that. I have one of the DSA 0% forgings that I am going to take a crack at. I would be interested to hear your approach to milling out the mag well. Post here or PM me if you'd like. Thanks |
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LaRue billet lowers are cheaper than that 80% lower. Yah.. but the government will know you have a lower.. and LaRue produces tons of them while these are in small batches. Also LaRue has the equipment invested into it already to make all his products.. and that in the long run can save money versus this version where different companies are cutting into the piece of the pie (cutting into the profit). Remember.. there are a couple of advantages of having a 0%- 80% lower: 1. No need to register it with the government, hence no need for a FFL transfer. 2. Pride in building something yourself 3. Can have it custom to whatever you want. For example you can make your own Jolly Roger Pirate lower, or Zombie lower. 4. More choices on custom designs for type of calibers. If you get a 0%, you can have the magwell cut to use a Colt 9mm, or buy a 80% that has it already done. Note there's the AR45 which uses a grease gun magazine.. where can you get that? Any case there's more cases for doing it yourself. Cost does go up when you do your own.. that's just a plain fact.. but that's due to things I mentioned before. |
| I have to agree with the side against 80%ers. I am cool with paying $20-50 for 0%, but if you have the tools and skills needed to finish a 80% you can do a 0% so why bother with a 80%. You can buy a 0% and all the tooling for the same as the 80%s that I have seen. Its crazy they are even offered anymore with the ATFs new "opinion" |
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I have to agree with the side against 80%ers. I am cool with paying $20-50 for 0%, but if you have the tools and skills needed to finish a 80% you can do a 0% so why bother with a 80%. You can buy a 0% and all the tooling for the same as the 80%s that I have seen. Its crazy they are even offered anymore with the ATFs new "opinion" I think less people have the EDM machine to cut out the magwell. Milling is one thing for the fire control & holes, it's a different story about the cutting out of the magwell. |
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