Monday, July 27, 2015

Make a Cleaning Brace for an AR-style Rifle

One of the nice things about the AR pattern is it's fairly easy to clean. At its most basic, the procedure is:
  • Push out the lock pin at the back of the receiver.
  • Tilt the upper receiver up until it pivots on the pin in front.
  • Pull out the bolt carrier group.
  • Clean.
The problem can be keeping the rifle open to clean the bore and chamber:
  • You can lay it on its side.
  • You can take the upper completely off and hold onto it.
  • You can set the rifle in a cleaning stand and put something under it to prop it up, 
  • You can buy a brace that fits between the upper and lower receiver to hold them apart at the rear (preferably while you leave the rifle in some kind of stand).
You'll notice I did mention they make them. You can just buy one. Or, if you're cheap/ frugal/ 'Wonder if I can?' like me, you can make one instead.

I started out with a piece of heavy plastic (or delrin, or whatever it's called). There's a plastics company here in town than makes all kinds of stuff, including cutting boards, and some leftover pieces that they finish the edges of and sell as odd-size cutting boards. I picked up one (6" W x 12" L x 1" D) and cut it in two, using the two squares as places to whack my bullet puller on, or as a base for punching holes in leather/ rubber/ cork/ whatever, things of that sort. It's hard, and smooth, and a piece of it worked for this. You could use aluminum, or steel, or anything else you have available.

After some measuring I laid out guide lines on one edge (oversize, on the 'easier to cut down than add on' theory) and side.

Then it's off to the hacksaw and drill.

The AR family has a lug at the bottom-rear of the upper receiver that sticks down, and the takedown pin goes through it. (See Figure 8 in this illustration.)  The piece to go here needs a slot for that lug to fit into, and the piece that goes into the lower receiver has to fit inside the lug cavity.

The drill was used to make the end of the slot that the upper receiver will fit into, and yes, I got the hole a touch off-center. The hacksaw cut the sides to make the slot, and separated the upper and lower pieces. Edges not cleaned or trued-up here.

I had to widen the slot a bit, and narrow the bottom piece, and then set them in place to try for size.

Still a bit long; it'll need trimming. I also had to round all the corners on the ends to have clearance for it to fit at that angle.

A note about this material: it's soft -- I can carve it with a sharp knife -- but it's slick; a sharp file just wouldn't bite. So I had to use a rasp to do the widening and to narrow the bottom a bit. Coarse sandpaper would have cut it, too.

Then I needed holes for the takedown pins to fit through. A regular pen won't mark this stuff, and a marker was too thick, so I used the marker to darken one side of each block, then used a scribe (or wire or pin) to reach in and mark the bottom hole. The hole for the upper was 'figure where it should be and make a mark'; I could remove material if need be to make it fit. The rear pin measures .280", so I drilled holes just a touch wider in both pieces, and then tried it; trimmed it a bit to adjust and tried again.

It finally fit, which means the takedown pin will go through the lower piece, the 1/4" nylon screw I used would fit through the upper piece, and it all sat properly. I wanted to be able to adjust length, so I drilled a hole into each block and threaded it (3/16x24 in this case), and cut a piece off a long machine screw to fit. Which produced this:

It can be adjusted to hold the receiver more or less open. Yes, if you measure everything correctly, you could make this of one piece and not worry about the adjustment feature*.

Just for general knowledge: this was made for an AR-10 rifle, so the slot needed to fit around a piece right at .5" wide and the piece for the slot below about the same; an AR-15 receiver is smaller and would need the pieces sized appropriately.

*If it isn't necessary but you put it in anyway, it's a 'feature'.  I insist.

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