Machining an AR15 lower receiver

[doubleboost]

Hi
Willie
You are doing a fine job
Cracking pictures
John

[DaveH]

Willie,

Fabulous - some clever set ups


DaveH

[ScrapMetal]

(06-21-2012, 01:49 PM)TomG Wrote: Supposedly, lower forgings can be purchased directly from Brass Aluminum Forging Enterprises of Ferndale, MI. for $13 each. I haven't verified this, but the link with all of the contact information is on the forum at CNCGuns.

Tom

Thanks Tom. I'll look into that as well. I've got to warn you though, when my wife asks, "Why?" I am going to point the blame at you.

-Ron

[TomG]

(06-21-2012, 04:19 PM)ScrapMetal Wrote:

(06-21-2012, 01:49 PM)TomG Wrote: Supposedly, lower forgings can be purchased directly from Brass Aluminum Forging Enterprises of Ferndale, MI. for $13 each. I haven't verified this, but the link with all of the contact information is on the forum at CNCGuns.

Tom

Thanks Tom. I'll look into that as well. I've got to warn you though, when my wife asks, "Why?" I am going to point the blame at you.

-Ron

I've gotten more friends in hobby trouble with their wives than I can count...go for it.

[Highpower]

(06-21-2012, 04:33 PM)TomG Wrote: I've gotten more friends in hobby trouble with their wives than I can count... and proud of it!

Fixed that for you Tom.

[ScrapMetal]

Cripes! It's like having an AA meeting down at the local pub.

-Ron

[Highpower]

After all the machine work was done, it was time to start working on the finishing touches. Filing down and sanding the flashing that was still remaining from the forging seam running around the center line of the receiver, and filing & de-burring any remaining rough or sharp edges. A few spots of the fire control pocket needed a slight amount of scraping/sanding in order to hand fit the internal parts to make sure that they would function properly and have a minimum of side play inside the receiver.

At this point – under federal law in the US – this chunk of aluminum all by itself, is now defined as a “firearm”. Technically any frame or receiver with more than 80% of the machining already completed, defines it as a firearm. It doesn’t have to make sense… it’s just the law.


With the hand fitting done I shipped the part to a professional finishing shop to have it lightly bead blasted, Type III hard coat anodized, and dyed black.







The remaining parts were gathered and assembled
and this is the final result.

It is a dedicated .22LR rimfire conversion that mirrors another one of my rifles that is chambered for the usual 5.56mm / .223 Remington cartridge.
I’m extremely happy with the results considering this was my first effort with such an undertaking. You never know until you try.
Thanks for looking.

[TomG]

Excellent work Willie, you should be very proud of it.

And thanks a bunch for taking the time to put together the build thread. I'm sure it will be well utilized.

It seems that I remember something about some issues with the hard coat job. How did that all work out?

Tom

[Mayhem]

I have heard that the hard coat anodizing requires the parts to be slightly under sized, to allow for the thickness of the coat. I'm curious as to ho this affected (if at all) your build.

[Highpower]

(06-21-2012, 10:17 PM)TomG Wrote: Excellent work Willie, you should be very proud of it.

And thanks a bunch for taking the time to put together the build thread. I'm sure it will be well utilized.

It seems that I remember something about some issues with the hard coat job. How did that all work out?

Tom

Thank you Tom. Yes, I still believe anodizer overshot the current on their set-up or left them in the tank too long, or something. I own 4 different brands of AR's now and this is the only one I have ever had the surface layer pop off like it does.

There may have been a slight improvement after I have wiped down the surface with oil a few times now, but I can still get flakes if it gets bumped against anything. After test firing the gun a few times checking it for function (100% BTW... ) I noticed that I was loosing the finish on the extension lug.


That turned out to be caused from the rear of the rimfire bolt conversion rail. There is just the slightest gap at the rear of the upper receiver that allows the rail to move back and tap the extension lug during recoil, and pop off the anodizing.


So now I have turned a piece of Delrin about 1-1/2 inches long and put a short taper on the end, and stuck it inside the buffer tube. (See pic above.) Hopefully this will keep enough pressure on the rear of the conversion rail to keep it from moving back with every shot.

I'll just need to keep a bottle of Aluminum Black on hand to touch up the spots as they occur. Nothing else I can do I'm afraid.