80% recomendation please

Discussion in 'AR-15 Discussion' started by suzychapstick, Oct 12, 2013.

  1. suzychapstick

    suzychapstick New Member

    82
    0
    0
    http://www.gunbroker.com/Auction/ViewItem.aspx?Item=358827731
    I'm looking to make some receivers. The link above is the one I have in mind. My mind isn't totally set on it, or the preferences that I'm going to describe, because it may be you guys can tell me something better, or that I'm missing. I liked this one because it's billet, and it's supposed to be 7075-T6. I like the solid trigger guard also. It seems a little pricey, but if I'm going to go through the work to do it, I want it as right as I can. I'm asking for anyone else opinions or experiences with this before I buy. Anyone know of any other 7075 billet aluminum 80% brands? I intend on buying a jig, have seen them w/ so called hardened steel bushings, which seems like the way to go. Question lingering in my head about these, is if the outer surface of lower isn't totally flat, or once top plates of jigs are on, it may not sandwich the receiver right. Can anyone say a certain jig is better than others or more versatile for any reasons?
    Anyone ever had a problem w/ a certain brand of jig? I know you can say, well it should be milspec, well milspec has tolerances to, and I just have a hard time comprehending how any jig is going to hold it properly and secure?
     
  2. Steel_Talon

    Steel_Talon New Member

    1,766
    0
    0
    Easier to buy a lower and build it.. AFAIC

    \\

    Are your trying to avoid?:rolleyes:
     
    Last edited: Oct 12, 2013

  3. Axxe55

    Axxe55 The Apocalypse Is Coming.....

    7
    2
    0
    not for sure a person can manufacter firearm parts to sell without an FFL either.

    i think they need to contact the BATF and get some good information before jumping into this blindly.
     
  4. suzychapstick

    suzychapstick New Member

    82
    0
    0
    Thanks, but I'm not looking to sell. When I said I was looking for recommendations or advice, I meant specifically on finishing or building my own. I'm trying not to drift to far from the subject. I appreciate your posts though.
     
  5. robocop10mm

    robocop10mm Lifetime Supporting Member Lifetime Supporter

    11,380
    2
    0
    Unless you have access to a CNC machine (and a good one at that), and the ability to broach the mag well, an 80% receiver will give you a BUNCH of grief.
     
  6. suzychapstick

    suzychapstick New Member

    82
    0
    0
    Thank you ROBOCOP. But I'm confident I can do what needs to be done on a manual vertical mill. Now, I didn't know I had to broach the magwell though. I have seen others that I thought you'd need a file to get it there, but didn't know this one needed it.. I'm kinda looking for replies of people on the names of jigs and 80%s that they've used or done.
     
  7. suzychapstick

    suzychapstick New Member

    82
    0
    0
    well, I'll just go with my own thoughts on this. I ask for an explanation about fire control group measurements though. I sent the jig company three different links of 80%s I'm thinking of getting, asking if there jig would work. The company I'm planning on buying my jig from says " he doesn't know the measurements across the fire control group, if there milspec then my jig will work." Also they said it won't work on Hellfire 80%s. Now heres where I'm not understanding. It seems to me, that the jig is going to dictate to me where the holes for fire control group are going to be placed. Being I've got a chunk of aluminum that has nothing milled out to do with fire control measurements, I dont see how different 80%s could be milspec when there nothing there to begin with? Now If the witdth of the 80% or the measurements of the holes used to lockdown the 80% w/in the jig were different, then I could see a problem. Looking at the hellfire, Its outer shape does look a little different, so I'm not questioning why it won't fit in a jig. But to my belief, fire control group measurements would be the distances from the pin holes. ???? And if those aren't done to milspec, your standard triggers and firing parts wouldn't work properly. Am I right, or is the jig company kinda sidestepping the question or giving an indirect answer??
     
  8. clr8ter

    clr8ter New Member

    4,015
    0
    0
    If it were ME......and I almost did just this last year, (but the company I was buying from screwed the pooch on the delivery, so I just bought a complete gun) here's what I would do. Buy an 80% lower with the mag well complete, and the threading for the barrel done. All you will have to do is mill out the pocket for the trigger group, mill a slot for the trigger, and drill some cross-holes for the pins to hold it together. If using a vertical mill, and if you have some skill, you don't need a jig. What you do need is a print of the lower, which is available on-line if you look hard enough. Somebody here helped me out with that, I forget who, but you could probably look up the thread. It was just last year, or very early this year.
    I personally wouldn't put much stock in having billet, or a certain composition, just go with a forged one, a lot of them are, anyway.....
     
  9. suzychapstick

    suzychapstick New Member

    82
    0
    0
    thank you clr8ter, well I appreciate your views on this. If I were only doing one, I might gamble on doing it with a print and an edge finder. But, if I'm doing a couple, i think a 150 dollar jig, is a good insurance plan to eliminate any math mistakes I might make. I actually only intend on using the jig to spot the holes w/ a center drill from both outer sides. Then drill them undersized and follow up with a reamer that .001-.002 under. I can always hone it out if needed from there. I'm not agreeing with you on the forged ones or not worrying about the composition. My thoughts are, I trust the manufacturers of aluminum more than I trust a 80% manufacturer thats pouring aluminum in molds, for it to come out and truly be composed of whatever it's claimed to be. I've seen flawed forged ones for sale. They are visibly flawed by an air pocket on outside. If that air pocket were trapped w/in the aluminum, it wouldn't be visible, and marketed as normal. I think the extra dollars spent for 7075 would be beneficial over the 6061. At least that what I think. I think the threads your talking about are the threads for the buffer tube. I appreciate your post. I was actually losing hope w/ this thread. I'm still wondering if anyone can explain about the questions of fire control measurements I asked in previous post. thanks
     
  10. clr8ter

    clr8ter New Member

    4,015
    0
    0
    Mmmm, I think you are confusing forging with casting. In either case, I'm under the impression that either is done by people who specialize in that process. Ie., the guy forging the receiver is not the one CNC milling it. Many things are forged. Like wrenches, hammers, etc. How much stress do they take? More than an AR lower.......

    If you are doing more than one, so what? Do one step at a time, on all of them. (Production) Drill one hole, and set it up so you can swap them, and put the next one in in the same position. Admittedly, a DRO would help here, but wouldn't be necessary. From what I can tell, a jig wold be useless in a mill. The jig is meant to give the cutter a place to ride against, and to guide it. Not needed on a mill.
     
  11. suzychapstick

    suzychapstick New Member

    82
    0
    0
    Thank you clr8ter, I've been thinking about going jigless since you mentioned it, and my confidence is slowly building up. Yes, I was confusing a forging with a casting. I wasn't aware they did forging on these. Especially of aluminum ones. Anyway, I think the biggest challenge would be securing the 80% in a vice or to the table w/o a jig. I've been staring at a lower since you mentioned it. I have a cheap Tslot clamp set, for my bench press mill. It probably wouldn't be to bad for boring the pins, but to hold the thing upright for milling out the trigger well etc., I'm not seeing it right now, especially if I get one w/ a trigger guard. Any ideas or suggestions on holding the thing?
     
  12. clr8ter

    clr8ter New Member

    4,015
    0
    0
    Well, it appears to me that the spot on the receiver where the hole for the safety lever goes is flat and parallel on both sides. try grabbing it there with a vise. You haven't said yet if you have a DRO. (Digital Read Out) That would let you put a stop on the vise, so the part is in the same position each time. Then write down the numbers on the DRO when you get to end points, so you can put in another part, and go to the same number as you mill. You should be able to mill the whole pocket including the slot for the trigger guard in one position. Of course, it'll have to be turned for the 2 holes. I'd actually think about drilling the 2 holes 1st, so I didn't have to flip it over. Get the best drill bits you can find, and go way slow. Maybe drill slightly undersize and ream it, too. (You should know that while I know something about machining, I'm not a machinist, BTW)

    PS, if you need further assistance, it might be better to PM me, since I'm not getting e-mails when someone posts to a thread I'm subscribed to. Don't know why....
     
  13. Axxe55

    Axxe55 The Apocalypse Is Coming.....

    7
    2
    0
    just a curious question or a suggestion maybe, but what about contacting the people that make the jigs, and see which lowers they recommend with their jigs? just an idea that came to me last night.
     
  14. MisterMcCool

    MisterMcCool Well-Known Member Supporter

    12,990
    433
    83
    Someone advertised on the forum an 80% lower that required no jig. It was within the last month or so. Does anybody remember that? I will look.
    Found it but they are polymer. EPLOWERS
     
    Last edited: Oct 14, 2013
  15. suzychapstick

    suzychapstick New Member

    82
    0
    0
    The height of my vise jaws are about 1.350 and with the triangular part that the pistal grip slides over is going to be an obstacle. With that in the way, I can only grab onto about the bottom 1/4" of the area your talking about, and a width of about .800 because of trigger guard. So not much to hold onto there, and a whole lot haging out on the side that needs milled. I'm going to remove the jaws off the vise, and see what under them. If it's not to much work, I might be able to make some taller jaws out of some cold roll flat. It's either that or get a jig. No digital readout or anything fancy. It's just a medium grade benchpress mill. I got a vise stop and the vertical and cross feed screws are .200 per revolution and are marked in .001 incurments. I've got a dial indicator on a magnet for the quill, so I should be OK as long as I'm paying attention. The only two thing I need to watch out for is a mental mistake, and the table will walk a little if I don't take baby light cuts. Axxe55, yes, i did contact them, they say they don't know for sure if it works on other billets, but they say it will work on the ones they sell. I have a casting one right now, and I'm not happy with it. I'm going to be buying a couple other billets of different brands, so, I'll just have to play it by ear as we go. Thanks for the thought mr. cool. Thank you clr8ter.
     
  16. Steel_Talon

    Steel_Talon New Member

    1,766
    0
    0
    Have you checked this guys video?

    [ame]http://www.youtube.com/watch?v=SYUfcxnDSWg[/ame]

    Also there are several How To with delrin lowers etc.
     
  17. fsted2a

    fsted2a Active Member

    1,641
    4
    38
    I am an FFL now. You have to get a CL 7 FFL to manufacture a firearm for the purpose of selling it. That includes just assembling the parts and/or milling out your 80% lower. Either way, if you do it for the purpose of selling, you need a FFL.
     
  18. suzychapstick

    suzychapstick New Member

    82
    0
    0
    Excellent job steel Talon, I saw some other videos that were a waste. I like it.