[blfuller]

The claw mount bumps are not enough to attach a scope mount. The bumps are also machined to have a cut in them to interface with the feet of the claw mount. That and the absence of the proper G3 sight base is a no go for the claw mount. You may be able to attach something but your accuracy will probably suffer. It would have been better if PTR attached a picatinny rail to the top of the receiver. That's what I would do if I had a CA-3 and wanted to mount an optic on it. YMMV

 

[blfuller]

That phosphate finish is an excellent base for a spray on finish. Degrease thoroughly and apply your favorite finish to make it look like a million $.

 

[blfuller]

I thought about it, but if Park is the correct finish for a Portuguese G3, I will leave it as is.

Judging from the original trigger housing, it's pretty close.

CETME looks nice. Your grip frame was refinished after it was clipped to interface with the receiver. The original finish, or what's left of it, is what's on the end plate. Probably was manganese phosphate. To maintain the original appearance I would get it refinished to match or a replacement that was already refinished.

 

[blfuller]

Manganese phosphate is the same as parkerizing. There's three types of parkerizing, iron, manganese and zinc. Manganese is the dark gray and zinc is much lighter in color. Manganese is typically the one used for firearms these days. Zinc was more prevalent back in WWII. Iron is typically used as a primer for other finishes.

"Parkerizing" is a commercial term named after Clark W. Parker, along with his son Wyman C. Parker, working together, set up the Parker Rust-Proof Phosphating Company of America in 1915.

 

[blfuller]

Sight elevation adjustment is covered here. A hemostat or needle nosed pliers also works for elevation adjustment if you don't have the proper tool.