The way I recall the Whitworth tap I just bought and chased grip screw threads with was listed both ways. BSF=British standard fine, which is the fine version of BSW=British standard Whitworth(coarse thread). So whit.3/16-32 would be the same as 3/16 BSF.
Here's a thought, did the original post seek larger diameter HEADS for the grip screws? I've noticed that this is the case for Erma La-22's; but since I am away from the guns in question, cannot say right now. The Erma grip screws have a significantly larger head diameter, so if thread size and pitch somehow match, they could work where this would be needed--or turned down a tad if the dia. is excessive.
David Parker
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