Anyone out there have a jig for the 80% lowers out there they want to rent out?
Which ones are the best/easiest.
I purchased 2 casting from Tannery shop and another forged  80% on ebay.  I figure I have three chances to suceed...
Give me some tips/things NOT to do.. Thanks

I'm new to building 80% ARs myself. I just started one so I don't have any tips for you yet. The best source of information as far as finishing a forging is: http://www.roderuscustom.tzo.com/cgi-bin/ib3/ikonboard.cgi
That place along with this forum has all the information you need. I just bought some setup blocks over there which are almost as good as the jig.

Good luck.

Check out Ace Arms.

[url=ar15.com/forums/topic.html?b=3&f=4&t=148435]BIY lower biuld sites[/url]

Tips on 80% lowers:

This is what I found, YMMV

Have an upper on hand before you start
Have a lower kit on hand before you start.

Several of the hole sizes on the print are unclear/incorrect. Having the parts on hand allows you to double check before you drill.

Have several mags on hand to size the magwell.  If you plan to use thermolds or orlites, use one of those.

If you have to open the bolt catch slot, move it toward the magwell, not the trigger.

Use reamers if you can get them, an adjustable reamer works great on the safety hole.

Buy a NEW set of drills before you start.

Have a file card and use it, the alum chips really clog a file.

Take your time, measure twice, cut once.

Edit to add:

Plan to drill the counter sink for the rear takedown pin before you drill the hole, otherwise you will need a piloted spot facer. A "bullet bit" works well here.

To drill the bolt stop roll pin hole:  measure and center punch (with auto-centerpunch) the hole location from the rear.  Start hole with small dremmel ball cutter.  Now you can hand drill it with a 12" bit, very easy, no jig or press needed.

Also, use oil on every hole you drill, will keep the bit cleaner and the holes will be more accurate.

I am just about to start on a couple of 80% lowers.  I bought an OSI jig from TangoChaser off the EE here.  I am wiating for it to come in the mail...  [:)]

I have accumulated all the drills, taps, reamers, end mills, etc. that I think I will need.  I have a Bridgeport at my disposal at work, as well as a nice drill press at home.  

I can't wait to get to get started.  I want to finish one in natural aluminum, that is, buffed out.  To me, finishing the lower is going to be more difficult than the machining.

Another observation:

The available blueprints are for a forged lower.  The cast lower is not the same size, some webs and sides are a little thicker (10-20%).

This doesn't make any difference in a majority of the work you have to do, just be carefull when measuring depth from a side face.  Another good reason to have all the parts on hand.

Also, castings tend to shrink when cooled, and they shrink more in thick areas than in thin areas, just like cast bullets do.

I have seen several of these castings, none were square as received, not far off, but needed some work.

They have some nice jigs on e-bay. Just type in AR15 M16 in the search window. A lot of stuff will come up you have to sort through it for the jigs. I think they are 4 or more days from the end of the auction. I saw them the other day and started to bid on them. You could buy them for a little over a $100.00 (I think). Check it out they looked real nice.

There is a guy over at Roderus that is selling blocks for finishing 80% lowers.  Looks interesting compared with the OSI jig.

Check it out...

[url]http://www.roderuscustom.tzo.com/cgi-bin/ib3/ikonboard.cgi?s=3f02cae90140ffff;act=ST;f=11;t=262[/url]

Anyone in southwest VA have a drill jig? Want to rent it or sponsor a Lower Completion Party? [:D]

It is pretty easy to make a jig for the AR, and a bunch cheaper than buying one.  I used a piece of 1/2 inch steel plate that I picked up at a local welding shop for a couple of bucks.  Then i downloaded the drill jig template from Roderus website, and glued it to my chunk of steel. Then I drilled the template, and shimmed the template to lay flat on my lower, I used the mag button hole as the common hole and stuck a drillbit through the mag button hole on both my lower and my jig. I carefully lined everything up and drilled away.  There is no provision for the buffer hole... you need to do that one the old fashioned way.

I tried to get a northern Ohio group together in the Hometown forum...  I had no takers, so I going it alone.

I'm haunting the Hometown Forums too.  Good luck.