John I have conventional hex head M4 cap screws & possibly flat heads too. But I think they are 0.7 pitch. Can you confirm what you require? Something tells me they are finer pitch. But 4mm seems big, what tool does this go into?
top pic - Might be a long shot but assuming correct fastener if you chucked a blank of material, made a shallow depth M4 threaded hole on end, bottom out screw into hole & angle profile whatever the insert seat angle is...
bot pic - Alternately if you found the right pitch but longer length, make up a cone spacer thingy with seat angle. It might not be pretty but would be functiona
I've used this Ebay seller on metric stuff & he is speedy fast (or at least was). The weird thing is the envelopes say Toronto so could be he is re-packaging?
https://www.ebay.ca/str/regansstore