Once apart, the parts show a 1911-like linage.

When I get a milsurp gun with lots of Cosmoline or oil on it, I find that a bath in mineral spirits does wonders at cleaning it up.

I placed that parts in a plastic pan and get the brush and mineral spirits to work.

I use a brush and just scrub the parts.

It cleaned right up with no problem.

After drying the parts completely, I blew the parts off and sprayed them with WD-40 and wiped them down again.

Then I started to put them back together.