Billet AR180B Lower, Project Defiant (range report post #92)

Are you going to have to send it to the RCMP Firearms lab for them to "verify" it? Because if they have to read that in person, it would make me so happy....
When I tried to register my other lower, all they told me to do was e-mail them pictures. I never heard back after that. Hopefully this one actually gets registered.

I sort of hope they have to verify it, but at the same time I don't because then they will have it for years if not forever. The RCMP likes to stall on things like this.
 
Finishing it up today. Just need to mill the fire control group pocket and cut the mag well.

Had my first major f**k up last night. Got in a rush and didn't double check my coordinates and I bored the buffer hole slightly off to one side. This is only a cosmetic issue but it pissed me off to no end. I usually double check and re-check my setups, but it was getting late and I wanted to go home. I had dialed and shimmed the receiver so the stock would be perfectly straight, then I dropped the ball by not setting my zero properly to the center of the receiver. It's still usable but not my proudest moment.
 
How many repositionings and tool changes to get to this stage of completion? I'm guessing your machine doesn't have automated tool changes?
 
Yes, we have an automatic tool changer with 24 tools. A production machining center is useless without a tool changer. For a one-off job like this, I don't load all the tools in advance, I load them for each program. I've probably removed and loaded the same tool a couple times. Not very effecient, but I'm programming as I go and don't know in advance what tools I'll use.

For this and AR15 recievers there are a minimum of 7 groups of operations. Right side, left side, front, back, top, bottom, and the grip screw hole. I'm doing probably 8 or 9 since I'm leaving some steps out until the very end (like the trigger guard slot). Ideally, I'd be doing this on a 4th axis fixture, which I have figure out to be able to do in 3 setups. One of the setups would be just to drill the grip hole and I'd do that off the 4th axis fixture. So basically, two setups would finish the receiver then just stack a bunch on another machine to drill nothing but the grip holes. If I was in production, that's how I'd do it. The machine could run lights out with multiple recievers stacked on the fixture.
 
Finishing it up today. Just need to mill the fire control group pocket and cut the mag well.

Had my first major f**k up last night. Got in a rush and didn't double check my coordinates and I bored the buffer hole slightly off to one side. This is only a cosmetic issue but it pissed me off to no end. I usually double check and re-check my setups, but it was getting late and I wanted to go home. I had dialed and shimmed the receiver so the stock would be perfectly straight, then I dropped the ball by not setting my zero properly to the center of the receiver. It's still usable but not my proudest moment.

If you're anything like me, you'll stare at it and get madder and madder at it until you cut a new one.
 
If you're anything like me, you'll stare at it and get madder and madder at it until you cut a new one.
They plan was always to cut more than one. ;)

I have two uppers, plus the idea was to cut this one out of 6061, make the necessary design changes and then cut two out of 7075.
 
Very nice work - just curious, if a person owned a prohib AR-180 and acquired a lower like this, would they be able to run the prohib upper on the non-restricted lower? This could prove interesting.
 
Very nice work - just curious, if a person owned a prohib AR-180 and acquired a lower like this, would they be able to run the prohib upper on the non-restricted lower? This could prove interesting.
What is the firearm? The receiver. You should know this by now!

I see no reason you could not run an AR18/180 upper on a non-restricted lower. Of course, the RCMP might throw the variant claim around to mess with us.

My plan for one of my uppers is to re-barrel it with a 14" AR15 barrel.

All done.
volkarms_xr1.jpg
 
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