My Magazine Well Dimples

Info on my custom jig work...

I started with the biggest bolt I could find from Lowe's.  I think it is a 1" diameter bolt... I chose to make this similar to my X-Y dimple "jig" (see below) and use the head of the bolt for the female side of the jig.  I found a smaller bolt for use as the male side.

Milling the bolt - I have thought and thought about how to do this and the best way I can think of to keep the jig from being "seized" after pressing is to use a 3-part jig.  Since I "conveniently" have a bunch of 1/4" steel stock laying around, I started by cutting a 1/4" section from the bolt shaft.

    

I took it down just a bit more than 1/4" to ensure a clean surface, so I have room for a standard washer.  So technically it is 4 parts :)  Here are all the pieces in place.  Note how the butt-end straddles the dimple to allow dimpling of the other side:

    

TESTING

Needs some tweaking - 

I wanted to show my failed attempts... I am fairly certain that the edges are too squared and causing the metal to shear.  So my next step will be to file/dremel a convex surface on the edge of the male jig.  You can see the tears in the metal:

Usage.  I measured the position to place the jig and marked with a sharpie.  Hold in place and close vise.

TEST #2:  Success

    The sharpie marks are to help me align the male side on the outside... if the jigs are not in alignment, the edge of the die that has the least clearance will shear the metal at the edge of the dimple, effectively "shaving" a tear into the receiver.  You would need to weld this tear closed if this happens on a good receiver.

The edges of this scrap were wrinkled - I don't anticipate a real receiver having this problem...

           

Fits well with a mag...         

 

This is the layout I am going to use on the receiver:

The rails interfere with the jig, so some cutting is going to be needed...

Test #3 - Failure.  BIG Failure.

There's a really loud disappointing "POP" that went along with this:

The edges of the male jig press too tightly against the corners, and inevitably causes a stretch on the edges.  To fit, I will need to round the male jig a bit more.  The current jig is too squared to properly distribute the pressure across the surface of the receiver.  

Test #4

In an effort to correct the pinch, I did two things:

1. Opened up the female side another 1/16".  

2. Rounded off the male jig:

   

 

Here are some pics of the testing to identify the problem... note the crease around the edge...

                

 

THIS NOW WORKS!!!

Here are some "proof tests" of the reshaped jig used on some 16-gauge sheet metal:

Usage

Laying out reference lines on the female jig:

         

Reference lines for the male then marked on the outside of the receiver:

    Clamped in-place and ready:         

Pressing the jig:

            

Results:

            

Note how the back end of the jig straddles the already-dimpled side: 

   

Test Fitting the Magazine:

This was done on the failed receiver, but gives a good feel of the final fit.  Nice and snug!

The dimple on the right in this pic was made after the enlargement... I think I like how it forms in the receiver better than the "squared" look of the original.  Looks more like the factory ones I've seen...

Repaired Dimples:

I was able to get my friend to MIG the torn seam.  Time to dremel...

... and it turned out quite well: