I have an old brass porthole which I have re-fitted in a new front door and some of the machine screws are playing hard to find. None of the chandlers stock brass machine screws anymore, Fosters can probably order in boxes of 100 but I only need a few 1/4" by 2" and 2 of 5/16" by 2" (just had to have different size dome heads).
Any idea who may stock these, alternatively will a stainless screw with a brass dome nut fizz? In the spray zone but otherwise under cover.