Can you get a conventional shank / long series drill bit that would do?
I must admit I’ve recently been trying a few different hex shank bits.
The only reason I’ve been trying them is that I can get away with just carrying my impact driver if I‘m putting up a light or something, but I’ve been somewhat underwhelmed by the quality, especially as I tend to have decent conventional drill bits.
I’ve tried both Bosch and Milwaukee and neither seem great, either for concentricity (they both use a two piece bit) or for durability, though the Milwaukee seem to be the better.
I have been using some masonry bits (yes, I know it’s the wrong tool for masonry, but for small holes in brick it's fine) and have been using these Armeg bits, which are way better quality. They’re forged in one piece for a start, seem to be exactly concentric, and good quality.
They also make a Cobalt bit for metal. I haven’t tried these but if they are comparable quality to the masonry bit they will be excellent.
I think they are one of the few manufacturers to offer hex shank Cobalt.
The downsides are that Armeg are a British outfit and I don’t know if they have distribution in the U.S. They are also geared to the electrical trade, so offer only a limited range.
Are you able to utilise a Japanese spec bit? The Japanese seem to get the absolute most out of their impact drivers so just about everything seems to be available in hex shank. Can’t believe they don’t offer a good HSS drill bit.