Red dot mount Glock 20 Springer Precision Mount or has anyone done a Lone Wolf drill And tap job ? mounting vortex venom or fastfire3
I am not a fan of any "mount" that places the sight any higher than directly on the slide, or melted into the slide (assuming you mean a reflex/holographic type sight). Although the bore axis of Glock pistols is more narrow than most, it's still too high, especially with the additional hardware between the sight and slide. Drill/tap is good, a melt is better (but expensive, and permanent). Lone Wolf's machine services are top-notch from what I've seen. Choose your sight, disassemble the slide (it's OK to leave in the FP channel sleeve, but make sure to tell them it's there), send it in with the sight, wait for return. Simple.
If you have machine work done, more than just a drill/tap, you MUST remove the FP channel sleeve, and purchase a new one (likely to be destroyed upon removal, and correct reinstallation is critical). My R/R success of the sleeve is about 75%, but it wasn't always. I've done a bunch, and I still keep a couple extra on hand.
If you have a mill (or a drill press with milling vise), most things you can easily do yourself. I do, and I prefer the drill/tap method. It's simple, the least intrusive, and doesn't limit sight choice to just one before milling is again required. Also consider the sight brand, as a FF3 drill/tap mounted is actually lower than some of the big $$ sights melted. This greatly departs when using a dovetail mount adapter, and they really suck by comparison, for a few reasons.
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I'll add that Burris customer service is very good. Very quick to respond with a replacement solution, only a bit slow with the return. I shook apart a FF3 with my .460 Rowland, and they replaced it, no questions asked. I attribute the failure to a couple hundred rounds fired with it mounted on a dovetail mount. Drill/tap mounted seems to be much less violent on the sight.