This jig is used as the bucking bar for riveting and to position the trigger guard on the receiver. Start with the .25" x 1.500" x 6" piece of steel. Mark a center line length wise and drill a .375" hole 1.750" in from each end. Using the jig saw with the metal cutting blade make two cuts length wise from hole to hole. You will now have a slot 3" long and approximately .375" wide.
As you can see the trigger guard does not just slip in. You will now need to finish the slot with files or the Dremel. Square the ends and make the slot only as wide as is needed for a tight fit. The front of the trigger guard is wider than the rest and will also need slight grooves for the mag release rivet to slide through.
This is what you should end up with. The trigger guard fits in snug and dose not shift or wobble when it is fully inserted. Next you will need to mark and drill/Dremel the rivet head detents. With the trigger guard pressed firmly into the jig mark the center of each of the five rivet holes. Using the 5/16" drill bit drill a shallow hole for each rivet placement. Using the Dremel with a grinding bit shape each hole to fit the rivet head almost flush.
This is how the trigger guard riveting jig is placed for use.
Next you will make the rivet punch. It is very important the ends be square on this part. Using the piece of .500" steel round stock make a notch .125" deep and 1" high staring .625" up from one end. This will be used to set the trigger guard rivets.
The next step is to rivet the trigger guard/mag catch in place. If you are doing the 80% receiver this is where you will need to drill the trigger guard rivet holes. Using the vise grip pliers position the spacer plate at the mag well opening and lock it in place. Drill the rivet holes with the .156" bit.
Now you will start the riveting process. Attach the trigger guard/mag catch and the mag spacer with the two 8-32 screws and nuts. One screw in the front and the other in the back on the other side. This will keep the assembly tight and straight during the riveting process.
Next insert rivets in the other two holes and put on the trigger guard jig. Place it in the bench vise and snug it against the trigger guard. Use a piece of .250" scrap under the rear rivet hole (Do not use the rivet yet.) and clamp the receiver to the jig. Do not over tighten as this may deform the receiver.
Use the rivet punch as shown to crush the rivets. I use a standard 22 oz framing hammer to do this. You are not trying to destroy the rivet. Go slow and light until you get a feel for the process. Once you have the first two rivets set remove the screws and set the other two. When this is done set the rear rivet and your done.
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