Had to go to expensive stainless surgical instruments instead. I went to
all
stainless screws on my planes, but it seems like the heads are easier to
chew up.


That's no surprise, as there are many kinds of stainless--and I don't know
enough about metalurgy to offer advice on which to use.

Try mentioning the problem to your supplier, if you have not done so
already, as they may have similar hardware in a harder or tougher grade.

Peter