I bought a pre-framed double door to separate a room in our basement. The pre built frame around the doors is basically 1" smaller than the opening so I need to build a frame around the opening with 3/4" think material that I need to fasten to metal studs.
I was thinking of pine or something similar that comes in 3/4" thickness to build the frame then using shims to make everything leveled. Would metal screws work to fasten the frame I'm building to the metal studs?
There's also drywall so in order it would go metal stud--->drywall-->pine frame--shims-->pre built frame+door

 

Normally what would happen is you would remove the sheetrock on the face of the opening, then you can install 2x lumber, screwing it to the metal studs. That would be 1/2" +3/4", or 1 1/4" total, and you said you had a little play. It may work out. If your measurements don't work, then doing as you said with 1x dimension lumber would work. Regardless you will need 2 1/2" screws. I would opt for self tapping type, #6 or #8.

 

I tried with drywall screws that I had laying around they're fine threads and it's solid!! Are those drywall screws supposed to be self tapping?

 

Fine thread drywall screws are made for metal studs.