Trigger job question - Experts are welcomed!

[tony.1911]

I am doing my first trigger job today on a AXIS .223. After the job is done, I realized that there were some black, solid kind of oil (I believe so), was cleaned out from the front part of the trigger. It seems those are helping trigger pull smoother.
Should I put some oil back, like gun oil?

Any suggestion is appreciated!

 

[SkytopBrewster]

Clp