Scirocco Register

I put on an armour door plate today and I needed to swap one of the barrels on the drivers door lock. The screw/ bolt that secures the handle on the outer right side of the handle needed drilled out as it wasn't budging. ( Despite several soakings of WD40 from the outside and inside after removing the doorcard.) What screw / bolt number is this and is there any type that doesn't rust up as much?

The bolt part number is N0141313 and the spring washer is N0122224.

These are the bolts that are on the opposite end to the lock!