How to use the BRDE FSB alignment jig The use of this jig requires a barrel and FSB that is undrilled. It may be possible to use this jig for other purposes but the main intent is for the installation of undrilled FSB's on undrilled barrels. 1. The first step is to verify that the new FSB fits the barrel without excessive binding or force required to install. It may require a tap or two from a soft mallet to get there but that is normal due to tolerances. If there are issues check for burrs on the barrel and the bore of the FSB. The use of a round file and emory paper should take care of most of these issues. 2. Next install the handguard cap on the barrel and insert the barrel extension into the main block of the FSB jig. The block has a milled notch to accept the alignment pin. This is the most critical part of the jig and is where the alignment takes place. This should be a tight slip fit but a small amount of play is normal due to manufacturing tolerances. It the slop is excessive due to a small pin care needs to be taken to center the pin in the slot. This can be done by eyeball or feeler gauge. In most cases this will not be required. Another option would be to replace the alignment pin in the extension. With the barrel installed in the block tighten the soft point set screw located in the bottom of the jig block. This will lock the barrel in the jig. Set screw locking the barrel in the block Barrel hole and alignment groove 3. Now the FSB can be slipped onto the barrel. The ears of the FSB will slide down the 5/16" key stock alignment beam. 4. With the FSB in position, install the 8-36 cap screw through the alignment beam slot into the FSB sight post hole. Just get this screw started. Make sure the FSB is tight against the handguard cap and barrel shoulder. Now the 8-36 cap screw can be tightened down. This will center the FSB. Cap screw pictured without the jig top strap. Cap screw pictured with the top strap in place. 5. With the barrel and FSB installed in the jig we are ready to set up in a mill or drill press. In this case we used a mini mill. In any case, the objective is to set the FSB at 90 degrees from the spindle. With a large enough mill or drill press table the main block of the jig will make this set up easy. In this case the barrel is held by the vise and the jig block and machinist level is used to set up. Once the FSB is set, a #31 drill is used to drill for the taper pin holes. Here the #31 bit is centered by eye on the FSB pin pads. With everything secure and set the holes can be drilled. 6. With the holes drilled, we can change over to a reamer in the mill or drill press and ream the holes to take pins. 1/8" x 7/8" straight pins or standard AR15 2/0 taper pins can be used. I use the standard 2/0 taper pins. It is also possible to remove the set up from the mill/drill and do the reaming of the pin hole by hand with a ratchet and tap socket or drill. When using a straight pin, ream to size and install the pin. If using a taper reamer the key is to take your time and test fit the pin during the process. I have found when doing the final drive up, the taper pin will seat about a 1/16" further in to the hole. If you want to remove the FSB once finished I recommend spraying down with lube and rotating the FSB a few degrees both ways to remove any chips or burrs. A soft mallet is typically required. Once off you should see nice pin grooves like this.