I ran into this problem before, ending up buying some cheap shit from AliExpress (3.3mm drill for an M4 thread). But there has to be a source here in Phnom Penh as well. The current the object of desire is a 6.2mm drill

Did you check the Global House home improvement store in Sen Sok? Huge array of home tools (Draper, DeWalt, etc) & equipment there. That said, I needed particular thread/size bolts for a small home fix job once, and I ended up finding them at the home improvement place on Mao Tse Toung - can't recall 100%, but think it was called Home-Fix.

Thanks guys. Global home I had been a while before, they have just the ordinary sizes. I know that I will get a lot of laughter now, but for my staff the Berrylions fit best. They instantly kill any Bosch drill, but the Berries last a couple of attempts. I prefer any HSSCO5 drill with good centring capabilities, but gave up completely on this here.
Yes, Home Fix has a nice selection of tools, however I prefer an other shop on the other side of the road, around 100m more in the direction of the Chinese embassy. The trick is not to buy the drills from the store, they have a small table close to the cashier and those drills (which are basically 100% the same) cost just 50% of what they cost, if you get the pack from their store.
Makita I know, but had totally forgotten about, thanks for reminding me, I will pay them a visit tomorrow. DeWalt I wasn't aware, I will check that out tomorrow as well. However I got very curious about that shop willyhilly mentioned, however without a name or picture it might get hard to find, because this road has hundreds of tool shops in this area...

the 6.2 I am currently chasing is for aluminium, so either way would do the job, although I seriously doubt, that there are drills in 0.1mm steps available for wood