Specific TYPE of bits to enlarge gas port on nitrided bbl?

[FartinSpartan]

Hi,

If it turns out I will need to enlarge the gas port any for a build I'll be working on, I am curious if there are a certain TYPE of drill bits I should plan to use. (ie, HSS vs. TiN-coated vs. ABC-coated vs. carbide etc.) -- especially for that first "next size bigger" operation. The barrel is nitrided, and it looks black (nitrided) in the gas port, not unfinished steel. So I'm wondering if "not as good as carbide" bits would have trouble especially the first one.

Plan would be to enlarge a few thousands at a time. (have been reading here).

Am planning at this point, I have not even measured gas port yet.

Thanks,
FartinSpartan

[FartinSpartan]

Nevermind. Found everything I needed here:

https://www.ar15.com/forums/AR-15/Gas-P ... 12-761051/