Hi Jim
,
good question, I think we have to differensiate between screws and bolts (or screw and nut fastening). Most screws would have been used to fasten one object (wood metal etc) to wood. These metal screws were originally 'modified' nails which seem to have 'arrived' in Europe early 15th C. I say 'arrived' because the principle of the screw was known in the Mediterranean area but were made of wood. The european screws are reported as used in armour and in the manufacture of flintlocks. Fixing the firing mechanisms to the wooden stocks makes sense. Using a screw to fix armour...does not. There are modern 'self tapping' screws than are used to fix metal to metal, these are metal srews that have hardened threads that are 'screwed' into a slightly undersized hole, the 'cutting' action of the thread through the hole provides the 'grip'. If this type of screw was used to fix armour there would be threaded parts of the screw pretruding...which would have to be cut and re-worked......bearing in mind the time and skill to produce one screw...it would be better, quicker and stronger just to use rivets.
A 'nut and bolt' or the 'screw and nut' however, would be better suited. It would take a long time and effort to make one nut and bolt ....and because they were handmade they were 'matched' to each other ie a nut made would not 'fit' another bolt/screw except for the one made for it. The advantage of the 'nut and bolt/screw' would be that armour sections could be removed for repair and then re-bolted together. But the time and effort to manufacture them would suggest than riveting would be the better option.
With mechanical manufacture of screw threads, thread sizes became standardised and were much more quickly produced. This meant that nuts and bolts/screws were interchangeable...as long as the threads were identical.
As regards sword hilts....hilts / guards etc could easily be replaced if fixed with bolts/screw and nuts ...after the standardisation and industrial manufacture.
I am trying to find evidence that 'screws' (bolt type) were fitted to threaded hole ....rather than a 'nut' with swords...in 'earlier times' , but so far I have been unsucessful
( other than 'threaded pommels' ) I don't know about the construction details of the firing mechanisms etc for early firearms ...but I am sure we will see some soon
Kind Regards David