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Posted: 7/9/2003 9:10:48 AM EST
Hello.

I have some questions about completing a 80% lower receiver.

-How about fitting the top-plane ? (especially with the Tannery shop lower)

-Does any jig help the drilling of the pivot pin assembly, the trigger guard, the different pistol grip assembly holes and the takedown pin ?

-Which drill bits are needed for these holes ?

Thanks ! Thanks !
Link Posted: 7/9/2003 9:21:40 AM EST
[url=ar15.com/forums/topic.html?b=3&f=4&t=148435]BIY lower build sites[/url]
Link Posted: 7/9/2003 9:26:18 AM EST
I am currently working on an 80% Tannery lower... I have the OSI Super Jig (thanks again TangoChaser)... There is quite a bit of filing/milling to be done to fit various areas together before you ever get to drill/ream a hole in the lower. IM me or ask specifics.
Link Posted: 7/9/2003 1:01:12 PM EST
I did so much filing on my NOC lowers I felt like a secretary.
Link Posted: 7/9/2003 1:32:45 PM EST
[Last Edit: 7/9/2003 1:33:18 PM EST by NevadaARshooter]
Originally Posted By gaby_the_belgian: Hello. I have some questions about completing a 80% lower receiver. -How about fitting the top-plane ? (especially with the Tannery shop lower) -Does any jig help the drilling of the pivot pin assembly, the trigger guard, the different pistol grip assembly holes and the takedown pin ? -Which drill bits are needed for these holes ? Thanks ! Thanks !
View Quote
Its best to do it on a mill. Locate, drill and ream all holes. The use a end mill or fly cutter to take the top deck to 0.250 above the cl of the takedown holes. On the last question, ream the holes to final size after drilling undersize.
Link Posted: 8/18/2004 11:42:47 AM EST
Some answers to your questions....

1. YES all my Tannery "cast" lower projects required MUCH hand fitting to get the top plane into spec...be sure the top plane is in spec BEFORE you do any cross drilling!

2. YES definetly use a fixture to drill the pivot/firecontrol holes and such..I recomend the jig from
HCMP, it has provision for the extra pilot holes for the lower trigger guard and detent.
www.hicapmagparts.com

3. IMO, use only high quality US-made Colbat drill bits. make sre to center punch first to prevent your bits from drifting.
Link Posted: 8/19/2004 4:21:29 AM EST
check out footpounds.com for a compilation of links to 80% receiver manufacturers, tooling, "how to build," etc.
Link Posted: 8/19/2004 6:06:22 AM EST
i milled my top plane for a perfect fit, then located the front pivot hole, all other holes were indexed off the front hole on the milling machine, it went very quickly, the lower worked good, and is still in the closet, it will stay there, the cating is a cheap and very porous one i really do not trust it too much, i would like to get an 80% lower forging with the magwell already edm, or broached

but the price is too high, i will buy complete lowers
Link Posted: 8/19/2004 6:00:44 PM EST
Howabout this one?
Fixture
Link Posted: 8/25/2004 9:18:43 AM EST
Looks GTG
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