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-   -   80% recomendation please (http://www.firearmstalk.com/forums/f20/80-recomendation-please-98677/)

suzychapstick 10-12-2013 06:42 PM

80% recomendation please
 
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?

Steel_Talon 10-12-2013 06:50 PM

Easier to buy a lower and build it.. AFAIC

Quote:

Once you have milled out the 80% lower into a firearm, you CANNOT sell it or give it to anyone else unless you have legally registered it with the DOJ.
\\

Are your trying to avoid?:rolleyes:

Axxe55 10-12-2013 07:00 PM

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.

suzychapstick 10-12-2013 07:17 PM

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.

robocop10mm 10-13-2013 01:52 AM

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.

suzychapstick 10-13-2013 03:08 AM

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.

suzychapstick 10-13-2013 05:27 PM

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??

clr8ter 10-13-2013 05:45 PM

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.....

suzychapstick 10-13-2013 06:44 PM

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

clr8ter 10-14-2013 12:07 AM

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.


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