Any AR-15 "scratch" builders here?

[ctrmass]

Re: Any AR-15 "scratch" builders here?

I'm using 2 123 blocks under the FCG area with a good set of clamps (Teco)
It eventually grabs a big chunk of alum and moves in the radius area.
I realize I should have something and a clamp under the mag well area, but I dont have any stock to shim it up.
I've been especially careful in the radius area not to take a big bite because I'm using a 1.5" (IIRC) mill to avoid taking multiple cuts with a smaller mill. I do not have a dro.Yet.

 

[Highpower]

Re: Any AR-15 "scratch" builders here?

OK, I know what you mean now. It is hard to get the forgings to sit still and behave at times. Especially when you are using lubricant while cutting. No matter how tightly you have it clamped the alloy still wants to slide.

I have found these fixture plates to be most helpful, and they are simple enough to make from some 6061 plate.

I don't have a 1-1/2" end mill. My mill doesn't have the HP to use one quite honestly. Even though it does take some extra time to cut that radius with a smaller end mill, it still comes out quite smooth. I was a bit leery of doing it in steps myself (18 cuts w/ a 3/4" mill) but it comes out nicely and doesn't dig in as you noted.
I am an amateur as well and the one thing I have plenty of is time, and I try not to rush myself. When I get in a hurry, things are guaranteed to go wrong for me. :banghead:

Are you doing your own anodizing? If so I would love to see your process.

 

[ctrmass]

Re: Any AR-15 "scratch" builders here?

My mill is only 3/4 HP.
I'd like to do my anodizing, but to be honest I dont even have the $$$ right now to make a set of plates.
I may just end up duracoating or cerakote.
I've already used the Duracoat and it's pretty easy.

 

[Highpower]

Re: Any AR-15 "scratch" builders here?

Yeah, the Duracoat seems to be quite popular and I've seen quite a few good looking examples with that finish. I would like to know how well it holds up over time. I picked up some KG Gun Kote to try using on another project - but haven't gotten around to it yet. (Story of my life...)

There are several of us here that would enjoy seeing how your receiver comes out when it's done. Details of the procedure used are always welcome too. We all benefit from each others trials and tribulations, so keep us up to date if you can.

 

[ctrmass]

Re: Any AR-15 "scratch" builders here?

I've already done several 80% ers. Not much to see. Takes about 2 hrs on my small mill and no DRO.
Other than no finish and mfg markings, they look like a factory made them.
The 0% will be a challenge.

 

[Highpower]

Re: Any AR-15 "scratch" builders here?

Other than no finish and mfg markings, they look like a factory made them.

I would certainly hope so considering the factory already did 80% of the machine work on them.

 

[Highpower]

Re: Any AR-15 "scratch" builders here?

Finally got it back from anodizing.

 

[ctrmass]

Re: Any AR-15 "scratch" builders here?

Shweet Georgia Brown!
Looking good!

 

[Tom Griffin]

Re: Any AR-15 "scratch" builders here?

Looks good Highpower.

I read on another forum that raw lower forgings could be had for $13 from Brass Aluminum Forging Enterprizes in Ferndale, but before I could check it out, I found on at a gun show. Hopefully I'll find time this winter to lighten it up a bit. How did you deal with the small radii in the corners of the mag well? I've heard of people drilling small holes in the corners and milling the rest out, but that sounds painful. I was thinking of making a slotting attachment for my mill and cutting them with that.

Do you have the rest of the parts to put it together? All I've bought so far is a barrel but my Christmas list is full of interesting little items. The Sportsmans Guide is selling a 16" M4 barrel chambered for 5.56 with a 1:7 twist for $99. I got one on sale last month for $89. It looks pretty good and I understand it's made by Mossberg.

Tom

 

[Highpower]

Re: Any AR-15 "scratch" builders here?

I was thinking of making a slotting attachment for my mill and cutting them with that.

Tom

Tom, that is exactly what I did as well. I did lay out the inside of the corners by just touching them with an end mill to give me a visual reference, but I did not drill them through.



My "slotting attachment" was just a piece of 1/2" round stock and I milled a pocket on the end to hold a carbide insert. The "Armstrong" method was employed to power the slotter via the quill feed lever on the mill.



I locked down the spindle brake after positioning the cutting tip by eye. The bolt sticking out the side and a big stretchy band was used to keep the backlash out of the splines on my mill spindle. Not much there to speak of, but enough that I can feel a little give when twisting on the spindle.



I have all the other parts, and I'm working on fine tuning everything to get it balanced out. This one is going to be a dedicated .22 rim fire that will fully mirror a standard M4. Forward assist, bolt locking open on the last round fired, bolt release lever, will all function normally. I hope... :biggrin:

Because of the lighter spring rate on the .22LR magazines, I'm having to stone and polish all the parts to get them moving smoothly as well as making up a new bolt release spring. The standard spring rate is much too stiff and I need to find the perfect balance to make it work reliably with the rim fire mags. It's been keeping me busy for sure. But that was the whole point of the project.