i have done several sight changes from ramp to Partridge. its not as hard as you think. for sure its good to have the gun mounted sturdy ,but it can be done in a machine vice. make sure all is square first. i use a set of magnetic alm V jaws on the vice jaws and use copper /brass shims of equal thickness if the brl is tapered . dial indicate across the length of top strap for flat ..should be close, but more important is to have the sight perfect vertical. i use a little bubble level to start, again on top strap or top of rear sight blade. you can get very close with a good read on the bubble. start cutting off the front sight , take a few shallower end mill cuts till its very close to the sight base surface. look things over. double check square and level. you can then cut flush with base or surface. dial indicate on both side of the brl up and down with spindle to get the center set. put in a spot/ center drill and put a spot in a ways for a place to start with an undersize end mill . if blade is .125 wide , go under that with a bit smaller dia. run it in about the depth of the radius lug on the bottom of the sight. may need a two flute mill here unless you went deep enough with spot drill , then a 4 will work.
cut the slot as long as the lug is. here is where you want to make sure you figure out how you want the blade to look. flush with the end of the ramp or back a little..? the slot length can be a little over what you need so you can slide it back and forth to get your desired spot. you will need to measure the slot width and move the table y half of the amount left to take out of the slot. try the fit, still tight, then go back to zero/ center, and move the table that same half the other way and cut slot again. try fit. if still tight , take just tiny passes again on both side .001 or so till you can just about get it started. then you can tap it in and also tap where you want it to set before drilling your hole for the roll pin.
Roll pin is another set up 90 degrees from where you are. know the sights lug depth and make sure drill is up from the bottom of the radius so you get the whole drill diameter into the lug. if your have this all level , you can start with a small center drill and spot drill your point for the roll pin. then , peck in and out a little bit at a time till you get all the way through the base and sight lug . start and tap in a roll pin (1/16) to pass through both base and the hole in the sight. you may want to clamp the sight snug to the brl./base to make sure it stays seated at your desired spot before drilling. just my 2 cents on how i did it. Phil
