I've had the opportunity to work on many matchlocks recovered from shipwrecks (Atocha, 1622) (1715 Plate Fleet) 1733 Plate Fleet). The ones that I worked on were supremely simple in construction. There were generally three different sizes encountered; arquebus (.60's), mosquete (.80's) and wall/rail gun (.90's). The rail guns had a post on the bottom of the barrel to catch on a rail or go into a hole. The post had a hole in it for the ramrod. Never saw a ramrod pipe, just barrel bands to hold the ramrod in the stock. Some barrel pins were made of iron and some were wood. Underlugs seemed to be staked in. Ramrods were entirely resting in a groove in the bottom of the stock ( fully exposed). Only saw one light arquebus where the ramrod went into the stock for a short way. The locks all had only one small leaf spring to keep tension on both the tiller and the serpentine. Most had tubular rear peep sights with some notched rear sights dovetailed into the barrel. Front sights were staked into a slot and not dovetailed. A few had markings or letters stamped into the barrel breech or on the tail of the lockplate. The most notable changes between the 1622 guns and the 1715 guns were the exterior shape of the barrels and the forearms of the stocks. The 1622 guns were tapered octagonal and the 1715 guns were oct/rnd. The forearm wood of the 1622 guns reflected the barrels and were faceted. The 1715 forearms wood was round like the barrel. I assume these were simply stylistic changes over time. Virtually all of the powder pans were dovetailed into the barrel from the breech end of the barrel. Only two that I saw had the priming pans as part of the locks and those two locks were different from all the rest. Virtually all the barrels were between 39"- 44". There was a fire shield that went between the powder pans pivot point and was pinched into a groove at the breech of the barrel (obviously behind the vent hole). If I remember correctly, the heads of the bolts that held the lock in place were 19mm in diameter. A couple of the 1715 guns actually had barrel band retaining springs, like later flintlock muskets, but only at the muzzles. The stock shape was what is called Catalan, like a boot with only the downward curve and not upward curve. I saw none with a thumb groove. The miquelet escopetas exhibited the same Catalan stock shape, but with a thumb groove at the wrist. Hope you're not bored to tears reading my long post. James Levy