Thank you for posting this new picture. You may be right and there is no evidence that the serpentine is not simply hinged as in Peter Kunz reconstruction. However it also shows two unaccountable errors which would undoubtedly affect its functionality. The friction bar is made both too wide and too short. The admittedly poor illustration attached shows the friction bar is less than 1/4 inch wide and has an effective frictional length of about 4 inches . Which corresponds to the frictional area of early Wheellock wheels. Also in the section nearest to the handle the two horizontal groves are well defined but the rest of the bar appear worn. This may be circumstantial evidence that it did actually work.

In my practical experience of the vagaries of wheel lock ignition I find it difficult to see how the required frictional velocity could have been achieved simply by pulling on the operating handle. Furthermore as far as I'm aware no one has made a reconstruction that proves it actually works in the way it is described.
However I may have over complicated the problem and it is just possible that a short lanyard tied to the handle pulled sharply overcoming the pressure of the pyrites on the friction bar might create a velocity sufficient for ignition.

Looking closely I believe the friction bar is a separate part from the pull ring, with a rivet just above the juncture. Possibly a repair, or because the bar is made from carburized sparking steel while the pull ring is a softer alloy. Interestingly I found images of another reproduction which was sold sometime last year, and the gunsmith specifies that he produced a greater spark using flint in the device (demonstrated in the third photo!). I obviously have no insight into the accuracy of this reproduction, but as flint generates sparks by cutting (rather than pyrite, which is cut) this could explain why the original bar is very worn. With this in mind I'm considering if the the pyrite which survives in the device could be an erroneous addition, and has misled its interpretation. Matchlock's stylistic ID to 1525-30 isn't far from the earliest written mentions of flint snaplocks, so I don't think it's too outlandish of an idea.
Attachment 233938
Attachment 233939
Attachment 233940

You are obviously aware that the principal of ignition in flint as opposed to pyrites ignition firearms is different but the myth persists that they are somehow interchangeable. It probably needs re stating that with flint the steel or frizen is the sacrificial element and that sparks result from tiny particles of steel stripped from the hardened steel . With pyrites it is the pyrites itself that is responsible for creating the sparks . The pyrites is heated by frictional contact with the steel . Tiny fragments of pyrites are detached and ignite through exothermic reaction with oxygen in the air. Substituting pyrites for flint in a wheelock will obviously produce a spark , after a fashion, but the serrations of the wheel are quickly destroyed . For this reason flint should never ever be used in a wheelock.

Your point about the antiquity of the snaplock is I think a valid one. In the past I have tried to argue, not always successfully that experiments with snapping locks probably occurred at the same time as the evolution of the wheelock and that the idea of a chronological evolution from matchlock to , wheelock , snaphaunce to flintlock is an over simplification. The point about the Dresden gun isnt I think about whether it sort of works but whether it worked well enough and reliably enough to be considered a viable firearm. If it did then this would support Blairs point that linear friction bar ignition systems were the logical antecedent of the wheelock and could have been developed in the fifteenth century.

I was actually browsing an online gallery of early wheellock tinder lighters a few days ago and noticed they all had flints inserted (with unfortunate damage to the wheels from doing so!). After also seeing the flint-fired reproduction & the abrasion you pointed out in the original bar, it gave me the idea that the pyrite may not be original. From what I understand, both flint & pyrite require a hardened steel plate to strike against, only the principle of spark generation is inverted as you described. I imagine a detailed microscope or xrf study of the bar & residues might identify what was originally used.

I don't think I'll ever be convinced of the design as a viable firearm, and agree with the opinion that it is more likely an experimental curiosity, noisemaker, or elaborate tinder lighter. From what I understand, the chronology of early ignition systems is obscured by trade secrecy & their near-immediate prohibition in the HRE & Italian states, which were also the centers of development & manufacturing. What I'm very curious about is the apparent existence of very early invoices from Braunschweig which mention friction locks in 1447? I don't have a copy of the relevant book "Das Kunsthandwerk der Büchsenmacher im Land Braunschweig", but would like to find the origin of such claims.

I managed to track down this clip from Thierbach which discuss the Monks gun in the context of other friction bar ignition systems. Could any kind person help with a translation as I can't get Google translate to do it?

Great find Raf, it seems to describe the monk's gun operating with pyrite as has been discussed, with linear & oblique cuts to the friction surface. Fig. 52 is a cannon lock from the 18th century with nearly identical construction, while 54 & 55 are spring driven friction bar systems from the 17th & 16th centuries respectively. This is what I gleamed using machine translation, and I can't find any opinions in the text regarding the efficacy of the device.

What I'm most curious about now is Fig.56 from that book, which shows an early 16th century lock where the friction surface is the segment of an arc. Functionally this would be the missing link between the linear bar & wheel, but not necessarily chronologically.

Attachment 234797