Dave,
I'd put the first one also as Germanic, but earlier going by the lock. I believe converted about 1830, but made mid 18th C.
Second one, Balckns, or Turkish. V hard to say which. Even Russian. I'll guess Turkish by the engraving.
Third,
Belgian or French. There should be proofs I'd think. This style common over both countries.
4th & fifth, not sure.
The 5th seems a bit odd, the lock appearing earlier than the rest, and fitted apparently not too well aligned.
4th one,
Just looked at Blackmore;
There was a Charles Lambert about the right time period, Apprenticed to W'm Shepherd 1782, Free of gunmakers Co 1793.
Gunmaker, 19 miles road, Cannon Street 1793, 25 Crooked Lane, 1779.
(London)
It and no 5 could possibly be made up later from parts, as they seem to both have a somewhat cross-bred look to them in my eyes. Not an expert though!
Apart from lock, No 4 appears more French going by design and sideplate.
Richard.