80% AR lower

There is a wealth of information out there on the finishing the buffer area (drill and tap) The best info on the "home brew" lower is www.cncgunsmithing.co m

Some of his stuff is really awesome, good forum too.

na94 said:
This might be slightly off-topic for this post, but...

When tapping the buffer tube mount, how should one mount the lower?

I have been thinking of machining a complete lower from raw stock, and I figured that one of the first things I would do after facing the block would be to center-drill the location of the buffer tube on the mill, than transfer to a 4-jaw on a lathe and bore and tap to finished dimensions. I assumed that this would be okay since any movement after machining the rest of the part should be within acceptable levels. This also simplifies holding the part.

Now, if I need to hold an 80% lower in order to tap it on a machine, how do I go about that? I assume that this is something you do not want to do by hand, and milling up fixtures would be a pain, no?
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na94 said:
This might be slightly off-topic for this post, but...

When tapping the buffer tube mount, how should one mount the lower?

I have been thinking of machining a complete lower from raw stock, and I figured that one of the first things I would do after facing the block would be to center-drill the location of the buffer tube on the mill, than transfer to a 4-jaw on a lathe and bore and tap to finished dimensions. I assumed that this would be okay since any movement after machining the rest of the part should be within acceptable levels. This also simplifies holding the part.

Now, if I need to hold an 80% lower in order to tap it on a machine, how do I go about that? I assume that this is something you do not want to do by hand, and milling up fixtures would be a pain, no?
Click to expand...

Drilling in the mill and hand tapping is the easiest way. The hardest and most expesive part would be finding and buying the tap. It can be done in the lathe the way you said - the only concern is the piece is projecting 7-8 inches from the jaws which is, in my opinion, less than ideal for threading.
 
Pocketfisherman said:
DLask told me directly that the RCMP are thinking of closing the door on the 80% as we know it. He said they may make you register it from Dlask from the get go or kill it all together.

They are perfectly legal until you have "intent" to finish it. So basically, if you look at it during diner with a butter knife in your hand...

Get them while you can!
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There is a place in the US that sells them. I'm sure with a US mail forwarding service you could have them shipped here (seeing as how they are NOT firearms).

http://www.tacticalmachining.com/category.php?cid=22
 
Armedsask said:
Thread mill the buffer. Cheapest and easiest.... if you have a CNC mill.
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I do have a cnc mill.

I am not sure why anyone would drill when they could bore however.

I have never even thought about threading on a mill without a tap, and then only rigid tapping or with a tap wrench support in the spindle.

Thanks for the info, I will do some research.
 
Helix bore it with an endmill, then thread mill it. One thread mill can cut an almost infinite number of thread sizes. Plus, using cutter comp, you can creep up on the size and make a perfectly formed thread.

Is your mill capable of 3D motion? That is, moving all three axis at the same time? If hand coding, send me your tool specs and I can send you the G code.
 
Armedsask said:
Helix bore it with an endmill, then thread mill it. One thread mill can cut an almost infinite number of thread sizes. Plus, using cutter comp, you can creep up on the size and make a perfectly formed thread.

Is your mill capable of 3D motion? That is, moving all three axis at the same time? If hand coding, send me your tool specs and I can send you the G code.
Click to expand...

I don't have access to a CNC machine. I was under the impression the buffer hole could be finished with a standard tap and die set?
 
Finished with a hand tap, yes. With a standard set, no. The buffer thread specifications are not a standard size.

My documentation shows the following thread spec:

1 3/16 - 16 UN-3B Special
Major Diameter: 1.1875 min
Minor Diameter: 1.1200 - 1.1283
Pitch Diameter: 1.1461 - 1.1519 Special
 
Hummmm ... might sound stupid but I wonder. Whats the point of paying $220 for a 80% complete lower when you cant get a 100% complete for $149 or $160 ? (cant remember if blueline or kodiak is cheaper)
 
Armedsask said:
Finished with a hand tap, yes. With a standard set, no. The buffer thread specifications are not a standard size.

My documentation shows the following thread spec:

1 3/16 - 16 UN-3B Special
Major Diameter: 1.1875 min
Minor Diameter: 1.1200 - 1.1283
Pitch Diameter: 1.1461 - 1.1519 Special
Click to expand...

How with the finishing coat I choose to use affect the threads?
 
volks_r_us said:
Hummmm ... might sound stupid but I wonder. Whats the point of paying $220 for a 80% complete lower when you cant get a 100% complete for $149 or $160 ? (cant remember if blueline or kodiak is cheaper)
Click to expand...


Think really, really, hard and you might see why many people choose this route.
 
volks_r_us said:
Hummmm ... might sound stupid but I wonder. Whats the point of paying $220 for a 80% complete lower when you cant get a 100% complete for $149 or $160 ? (cant remember if blueline or kodiak is cheaper)
Click to expand...

Some people like the challenge of doing things themselves. I had considered doing an 80% but figured I was too lazy and cheap to go out and buy the 70 dollar buffer tube tap and try to figure out anodization. I am sure when I have more time and money on my hands it would be an interesting project for part of a winter.
 
volks_r_us said:
Hummmm ... might sound stupid but I wonder. Whats the point of paying $220 for a 80% complete lower when you cant get a 100% complete for $149 or $160 ? (cant remember if blueline or kodiak is cheaper)
Click to expand...

Being able to engrave the fire-control settings to "Pax" & "Hiroshima" is reason enough. Being able to make up a serial number like "K0K1ER 5UCK5" is another good reason. Engraving it with whatever you want, custom colour, etc. It's all about getting exactly what you want.
 
For most, it's the satisfaction of being able to say, "I built this."

Also, my serial number trumps all, FUC68. My next billet lower is going to have C0CKPEN15 as the serial number, just because I will giggle when I get the registration.
 
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