No one could be any happier than myself about your shedding new light on one of my older posts (I joined the forum only two months ago).
Actually, the bolt action breech loading system has been employed with wheel-locks at least from 1540.
I attach some images of a combined snap tinder lock and self spanning wheel-lock breech loading harquebus (the snap tinder holder and iron "cartridge" now missing), the barrel bearing the double falchion mark of Christoph Arnold, Augsburg, ca. 1540 (an almost identical piece in the collection of Schloss Grunewald near Berlin bears the same marks together with the date 1540), and a short wheel-lock breech loading harquebus or pistol by the same maker and of identical date. I got allowed to take the photos of the latter in the Imperial Vienna collection 20 years ago. Its exceptionally fine condition strikingly illustrates the original impact of contrasting colored surfaces in those mid 16th century pieces!
You are doubtlessly right in assuming that such a costly and refined system would only have made sense if used together with pre loaded and readily primed interchangeable iron "cartridges". Only in wheel-locks the pan was an integral part of the lock and had to be primed manually prior to each shot.
Interchangeable breech loading with cannon was in use since at least mid 15th century. It took some time to get applied to harquebuses, though.
We know of some very rare breech loading break down action flintlock guns of early to mid 18th century date whose sets of spare cartridges are still contained in a leather collar, each of them equipped with its own frizzen and pan - perfectly ready and primed!
I enclose some views of one rare sample of such a rifle, ca. 1700 but re-stocked in mid 18th century, together with its original cartridge collar containing 11 numbered and rifled (!!!) iron cartridges, with number 12 inserted in the breech. I was granted to take the pictures in the reserve collection of the Princes of Thurn & Taxis, Regensburg/Bavaria, 26 years ago.
In all probability, mid 16th century "cartridge" containers for breech loaders looked very much the same.
Great mind job, buddy - and thanks for inspiring me to post the following attachments!
Btw, how do you like my photo archive?