You don't necessarily need new bushings just to put in hex grip screws. In fact if you remove the grip bushings you may be getting yourself into a mess of extra work. The grip screw bushings are usually staked in place, when you remove them, sometimes some of the staking acts as a tap and as you remove the bushing it cuts bigger threads or damages those that are or were there. Now you may need one bushing or a set oversize bushings ( $8 us)and tap (40 us)to put it all back the way it was. Try ARMCO at the top of the page for grip screws or fixing and oversize bushing if needed.