I have found them damn hard to smash correctly. I finally gave up and tapped the hole put a screw it it then welded and grown the top of the screw in. When I got finished you could not tell it from a rivet.

 

all my milled rifles had the bullet guide not installed.i just welded the rivit in from the bottom and rounded the head with the dremel.looks and works fine.

 

I use a bulk rivet. Turn the underside of the head to fit the bevel on the bullet guide rivet hole. Leave the domed head in place. I use a flat head punch set upright in a vise. Support the underside of the rivet on the punch face and set the rivet from the top with a punch & hammer. Use a Dremel with a stone of apprpriate diameter to remove material and fit the rivet to the bullet guide contour. Pretty simple.