Tools needed: drill press or lathe or mill, dremel, 3/8-24 tap(and t-handle), #31 drill bit(or 1/8" bit), #14 drill bit, G drill bit, L drill bit, Q drill bit.
Materials: two 3/8-24 x 5/16" set screws
1: remove all orings and the bumper from the bolt . Tape up the 2 #12 oring grooves so they are protected from nicks and scratches during drilling. most any tape will work, your just trying to cover the vital sealing areas from damage.
2:take the G drill bit and line it up with the bolt guide so there is a .050-.070" gap between the taper tip of the drill bit and the tapered part of the bolt guide(the tapered part of the bolt guide is right in front of the back #12 oring groove. Mark the drill bit with a sharpe where it is flush with the back of the bolt guide. This is how deep you want to drill with the G bit.
3:take the L drill bit and mark it the same way as the G bit except this time line the tip of the drill bits taper up with the back wall of the back #12 oring groove. mark the bit with a sharpe where it is flush with the back.
4:now take the Q drill bit and line the tip of it up so that there is a .050-.070" gap between it and the rear tapered part of the bolt guide. mark with shape where flush.
5: mount the guide in your drill press/ lathe/ mill and center the 3/16" allen socket on the back of the guide with the chuck of your machine. Drill first with the G bit, then the L drill bit, and finally the Q drill bit.
6:now take the 3/8-24 tap and tap the hole in the back of the bolt guide until the tap stops or bottoms out
7:Next mark 3 evenly space dots around where the rear #12 oring grooves taper meets the 1/4" shaft between the 2 #12 oring grooves. use the dremel and the #31 drill bit(or 1/8" bit) to drill the 3 holes. you want to hold the dremel at an angle so that the taper tip of the drill bit is parallel to both the 1/4" stem and the rear #12 oring groove's taper. drill until you feel the bit break through into the hollowed out center section of the guide.
8:remove the tape and clean the bolt guide with soap and water extensively
9:Now take one of the 3/8-24 set screws, apply blue or red locktite and screw in until the back of the setscrew just passes the 3 holes in the rear of the guide. *OPTIONAL- you can grind down the front and back of the setscrew before placing it in the bolt guide so that it is as low profile as possible. this will allow for the most volume possible.
10:Next take the remaining 3/8-24 setscrew and drill it out from the non allen socket side with the #14 drill bit. It helps to hold the setscrew if you thread it into a 3/8-24 nut and mount the nut in the vise.
11:Finally blue or red locktite the drilled setscrew flush with the back of the bolt guide and allow both setscrews 24 hours to dry. re-install the orings and bumper and your done.