In other words, if a barrel is already dimpled for gas block set screws, should any gas block work or would it have to be the exact brand/model that the dimples were created for?

I was thinking about buying a barrel that's got the GB set screw spots drilled, but if it's not a standardized placement as far as spacing and position relative to the gas hole, it would be more of a pain in the rear than it's worth.

The spacing can vary from one manufacturer to the next, but they will all have the rear hole directly opposite the gas port. Barrel makers usually only dimple opposite the gas port, the other dimple is usually up to you to drill.

OK.  The barrel I was looking at clearly had two dimples.  I suspect it's a take-off.  I guess I'll pass...

The most popular is 0.460" but they do vary.

brdengineering.com/p/technical

Syrac Gen II blocks are 0.500".



-Stooxie