Would it be posible to build an 80 percent lower using thus technique?
https://m.youtube.com/watch?v=tH-PaNugz9w
Were could i find the dimensions to help me cut the styrofoam mold
>>30662256
The threads for the buffer tube would be the hardest part to carve but it would be harder than a polymer lower, not as strong as a forged or billet I'm guessing.
>>30662358
I was thinking about that rite now it would be best to just leave it un threaded. Also i might as well go full 100 percent except for the threaded buffer part
>>30662256
TL;DR: Yes, kind of, to a point. Try it, but read up a little before you do (pic related). Also, I'm sorry for jargon but there's no other way to keep the post short.
The metallurgy here is a little difficult to get right; you're likely to end up with something that's weak and even porous unless you seriously think about how the casting cools in the mold and carefully select a casting alloy of aluminum (not soda cans). There's actual calculus involved in getting it perfect, but you might be able to do an initial guess with an entry-level understanding of casting metallurgical techniques. Otherwise, It'll be slightly better than a polymer lower.
As for the dimensions, the standard drawings detailing the shape of an AR lower are freely available. "AR-15 Lower Drawings" should get you all you need, but you'll also need to learn how to read shop drawings.
And as an M.E. student who's had to make some shit: Leave all the holes to machining. There is no way casting will give you holes accurately enough to fit up with all the pins. Make the receiver extension hole solid, maybe with a cone in the center to help with drilling it out. Make a jig or something to drill all the pin holes. For threading the buffer tube hole, get a tap. It'll cost maybe $50 at most.
Godspeed, anon.
>>30663432
forgot pic
>>30662419
the threaded buffer part is legitimately the hardest part of an ar lower to machine and requires specialized tools
>>30663578
>requires specialized tools
yeah, a tap
http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/taps-dies/ar-15-m16-receiver-taps-dies-prod636.aspx
I don't think that cast will be to spec.
>>30663432
Well I know calculus but this would most likely be trial and error. I realistically would like to leave every thing done except the holes for the safetys,top receiver assembly, buffer tube hole/threads etc
>>30665055
The answer is still "maybe, research it and try it." I'm pretty sure you could get by with casting in the pocket for the fire control group and the magwell, and anything that doesn't need to be precisely shaped/placed; those should be drilled/machined. More worrisome is that the cast will be too soft to hold up to the rigors of use. Maybe if you pick the right alloy, you can heat-treat it and strengthen the receiver after you're done poking holes in it. I still think it'd be inferior to a forged receiver.
Also, on a legal note, don't have too many iterations in existence at the same time. BATFE might decide that you're trying to get into the business. The good news is that casting alloys tend to be re-usable.
>>30666027
I'm sure just making a few to arm your friends and family would be fine.
