Bit size for sp101 grip screw

[65hoosier]

I am looking to buy a hollow ground screwdriver for removing the grip screw on my sp101 2.25"

Can someone tell me which Brownell's bit best fits this screw ? I came up with the 445-20 but noticed the Ruger set with 4 bits doesn't offer anything close.

 

[CMB69]

It's not that easy. Screw slots vary. Bit sizes are not that precise, they vary too. Often gunsmiths / hobbyists have to alter bits to get a tight fit. You can get bit sets at hardware and big box stores that cost a lot less than Brownell's and work fine.