Originally Posted by Untitled Agent
that's weird, could be you can't use the sentry for double 64 then. i'll test it out on an alt account next time i'm on.
Sounds good, let me know...
I'm gonna try using a different weapon second function and see if it will unlock then. The weird part about it is that I already had about 30 or so kills from secondary function while playing through the campaign, so it should have unlocked around 100 kills for me.
The fact that I had unlimited time/kill limit on wouldn't affect the achievement would it?