IIRC that is a #4 x 1.25" wood screw with a rounded head. The diameter of a #4 is around .112" which works out to 2.84mm and a length of around 32mm if you are looking at metric. I have not seen anything in that style/size/length for sale at McMaster Carr in standard or metric. You can get them in the right length and diameter, but they have a flat or oval head that is tapered to fit flush with the surface you are screwing into. One alternative is to get the countersunk heads and some finishing washers, but a #4 finishing washer is .375" dia so you'd need to measure to see if you can use something that big, as the rounded head on a #4 runs around .211" dia.
I also looked again and could not find the eBay seller I got the stainless screws from, sorry.
At this point, I'd stick with Fender pure vintage screws. IME one of the real values of an MIM or MIA Fender is the quality of their fasteners. They are much better quality than just about all the Pac Rim basses I've worked on, including the Fenders from there, but that's nothing new for products built in that part of the world. When I raced toy cars my first purchase after a new Taiwanese chassis kit was a complete set of replacement screws made to ISO spec 10.9 or 12.9 as they were worlds stronger and more durable than the included hardware.
Anywho, this would be my choice if I was looking for a better quality screw for pickup height adjustment.
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If you shop you can find better deals, just make sure it is the same part number before you pull the trigger.
If after you get the Fender screws, you are still having trouble stripping out the head, get a good #1 Phillips driver. A Craftsman driver from Lowes would work fine. If you have a Pac rim bass you might need a JIS #1 driver to get the old ones out.