If someone is a Magos, then I guess the proper way to address them would be Magos XYZ.

However, how would you address lower-ranking Tech-priests?

Cogboy? Metalhead? Greasemonkey? Tinhead? Spanners? Techie? Geek?

Joking aside, the various Tech-priest Ranks in Dark Heresy all have sample Titles, which you can pilfer. I'd say the proper form of address would be the Title of the priest, which would be tied to his function.

So the priests keeping the starship engines running are Enginseers, etc.

"Enginseer". "Tech-brother". "Mech-Deacon". It depends on the rank/personal preference of the techpriest in question. One techie that I had specialized in Medicae, and accepted "Doctor" as a term of address. Another character I had was a fairly irreverent Arbitrator who referred to the party techpriest as "Sparks". To be fair, he also dubbed the Moritat assassin "Psycho", and he himself went by "Sledge", as in the Hammer of the Emperor; the whole party had nicknames.

Why do they all have nicknames? You should know what the group is called.

Boss Gitsmasha said:

Nobody else is taking you up on this? I'll bite:

Gitsmasha, what are they called?

I think he means the names of the individual accolytes in the group, such as: Severine -> Sev

Also, gearhead.

Well now that's just not as fun. I thought they had a cool group name that was slightly inappropriate. Oh well.

Jeff Tibbetts said:

B.A.M.

(Anyone who gets that receives 1 Internet)

It annoys me that it's not B.A.M.F..

That would make more sense…

BYE