Finishing an 80% receiver

mfisher · Oct 1, 2010

From the looks of it, the 80% AR style 80% receivers could be finished off in just a couple of hours, using jigs (plus then debur, cleanup, prep and anodize). Also seems that the jigs aren't all that critical for locating cuts (assuming decent skill level, and capabilities to measure and indicate under 0.001), but make holding the receiver much easier.

I'm thinking of this as a one or two off personal use project, no manufacturing.

Never tried one of course. Any input on the need for using the jigs?

Do used jigs ever show up for sale? Leaning towards the AR-10.

Again, this is a for the fun of it, not for production or to save money over buying a complete rifle neccesarily.

Helix_fr · Oct 1, 2010

I've done 1. and there is a reason I did one, because 2 would have taken me to long. I didn't use a jig though, I went of blueprints and the artisian method of locating the cuts. It was quite a experience. but for 30 bucks more, you can have one complete. A jig would have sped things up a little I'm sure.

MrWetwork · Oct 2, 2010

The receivers are 100% capable of being completed without purchasing a jig. Just takes more time and a little more skill. The jigs are really awesome for drilling the through holes and holding it in a vice when you mill out the fire control group.

When using the jigs for the FCG we recommend not ever touching the plate that goes in the top of it and roughing the pocket out then taking the top plate off for your finish pass so you can measure where you are and where you need to be.

People who have done a few of these claim they can mill it out in about 20 minutes with the jig. I personally have never seen used jigs pop up for sale but you can always try placing a thread on any forum with a willing to buy used jig title and I'm sure somebody would respond.

biometrics · Oct 4, 2010

Try ar15.com forums

lots of help and information and parts available there for all AR type rifles.

Butch Lambert · Oct 10, 2010

Why in the world would you buy an 80% when a very top quality one is available for about the same price. Go to Stillers website. They are a very top quality CNC billet receiver. I paid $225 for mine and it was anodized also.
Stillers Precision Firearms
Butch

mfisher · Oct 10, 2010

As in the original post, just for the fun of it.

Yes, I could also start with a solid piece and go from scratch, but I don't want that much fun.

Rex TX · Oct 12, 2010

no paper

For some people, it's worth some time or money to have a receiver that never saw a transfer form.

But then deals like this can weaken one's resolve:

Surplus Arms & Ammo LOW15 Stripped AR Lower Receiver

mfisher · Oct 12, 2010

Don't mind the paper work, haven't had a problem in the past, and don't supect there will be one now.

That is a deal. Will need to look to see if it's available in 308.

Anyone care to actually answer the question?

HMC710 · Oct 16, 2010

0 - 80%

I've done a few, like you said, just for the "fun" of it and to see how hard it is (was). All of mine were done with the 0% forgings without the jigs, but I did buy the long drills and buffer tap. I think my forgings came from DSA if I remember. Check out Home Gunsmith Forums
There is a wealth of info there as well as some books and dvd's. You can build it by the numbers if you have the numbers which you should be able to find above. The vice plates are easy to make and if you can not do them, I would suggest not trying a lower. The hardest part for me was finishing the magwell. I am going to make a broach before I do another one. So to answer your questions:
1. No, you don't need the jigs if you can layout or measure the numbers (providing you have the numbers)
2. It's not any harder than dilling a hole in the center of a tube or making a keyway.
3. No, it's not cost effective.
4. Yes, it's a lot of fun, if you like making chips.
Go for it and Good luck!

wildhorsemfg · Oct 31, 2010

80% s from tacticalmachining.com are vary good done a few and they are perfect

Forestgnome · Nov 4, 2010

I used a jig on my first one, an 80%, then found the jig quite useful on my second one, a block of aluminum. Like others said, it's useful for holding the receiver while milling out the trigger group pocket and drilling the grip screwhole. Otherwise you'ld need to carefully set it on spacers to get it square to the mill or drill. I followed the instructions on the jig which said to reference off the top and buffer tower, which ended up being a mistake. My opinion is to reference off the front pivot making sure you're lined up properly at the bolt release. Those are critical areas. I made a jig to single-point the buffer threads on my lathe instead of using a tap.

HMC710 · Nov 20, 2010

Machining Lowers

Forestgnome, you are da man! Doing the buffer in the lathe is awsome. One area to get off with a tap is the buffer then you get interference with the carrier and it causes issues. I also use the front pivot to reference off of.

robrob · Nov 24, 2010

mfisher said:
Any input on the need for using the jigs?

Do used jigs ever show up for sale? Leaning towards the AR-10.

Again, this is a for the fun of it, not for production or to save money over buying a complete rifle neccesarily.

I've done a couple AR-15's and one LR-308 80% lowers (compatible with DPMS LR-308 uppers) from tacticalmachining.com They sell a kit that includes both the AR-15 & LR-308 jigs and one AR-15 80% lower. The jig isn't absolutely required but I highly recommend it. Using my manual mill it takes me about 4 hours to complete one. I'm definitely picking up speed with each lower (I'm an amateur metal worker and still learning the mill and lathe). You have to drill the hammer, trigger and selector holes, and mill out the trigger well. Everything else is done for you.

TM 80% lowers are $85 each for AR-15, and $160 for the AR-10 so you should probably learn on an AR-15 lower. I very much enjoy shooting my home milled ARs. Keep in mind these completed lowers are strictly for your personal use, I don't think you can even legally give them away.

I'm not affiliated with TM but I am a happy customer.

Rex TX · Nov 24, 2010

robrob said:
I very much enjoy shooting my home milled ARs. Keep in mind these completed lowers are strictly for your personal use, I don't think you can even legally give them away.

The way the law reads, you can't build one with intent to sell. If you build one for yourself and years later things change, you can transfer like any other weapon.

Plan on keeping it, but you aren't joined for life. At least that's the way I understand it

IANAL etc

adamsgt · Dec 4, 2010

I took four of the summer gunsmithing classes at Trinidad CO this last summer. One of the students was doing one of the 80% lowers and broke off an endmill deep in the receiver. Don't know if he ever recovered from that.

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