[andrew17]

Howdy, does anybody know what size the retaining nut for the replacement sight is for a glock?

Thanks a bunch.

[jungle]

Various tools from the sight makers or Glock will handle the job.
If you don't want to spend much, get a 3/16 "Craftsman nut driver #41977. Depending on the model Glock,you may have to thin the socket wall to clear the slide recess for the nut. The nut is faily thin so the socket lead in taper is best ground flat to gain purchase. Just use enough torque to about finger tip tight, any more can damage the small threads.
In a pinch a long set of forceps or thin needle nosed pliers will work.
Use red or "permanent" threadlocker.

[andrew17]

Ahh, big thanks jungle. Reason I asked is I noticed that my local Sears is having a closeout sale on their mini nut drivers. a buck each. Might be a good alternative to the rather pricey certified glock type tool.

[Rockstar]

Ameriglo sends a free front sight tool out with all their Glock sights. :)

[jrhines]

RS - If you use that nut driver, fill it about full of modeling clay. That will hold the nut inplace while you get it into the slide. I find they are easy to start this way. YMMV