Originally Posted By scudzuki:
I stand corrected. I have looked at a lot of barrels and never saw a one that was pre-dimpled.
As for those that are, since there is a drill jig available for dimpling barrels, I assume that the location of the setscrews is somewhat standardized.
I've used several different brand lo-pro GBs and while I've not measured them, they all appear to have the setscrews in the same locations.
Being as I have a machine shop in my garage, I've never needed either a pre-dimpled barrel or a drill jig.
They are not standardized. Some have different spacing, some screws have a different profile or are different sizes, some only have one screw while others have two. Also, some gas blocks are designed to sit all the way up against the ledge, while others have to be set back a little. If you look at the descriptions for the jigs, it tells you what style or brand of gas block it is designed to install for.
Not to mention, if I am not installing a set screw style gas block, I sure as hell don't want pre-drilled dimples showing through on my barrel.