Murph,
Research , which is always ongoing on Schofields, supports several things. During the production process as parts are made and inspected, two things happen; (1) the part's approved and and a sub-inspector applies his mark, or (2) the part is rejected and sent to the bone yard where depending on the part's problem it might be repaired and returned to the production line, or if not it might be retained for a non-military gun. S&W seldom threw away any part. Therefore in the production of civilian models, both 1st & 2nd Model Schofields, you will see parts with inspector's stamp and "naked"parts w/o inspectors stamps. These naked parts come from two sources (1) parts rejected by inspectors, and (2) parts made directly for civilian guns. Both types can be used on guns that show "US" stamps, as rejected parts that had the US stamp applied before inspection and were later rejected, did not have the US stamp removed, as that stamp did not have any bearing on whether the part was actually going to be used only on military guns. The only real guaranty a gun is a military gun is the final inspector's cartouche on the gun's stocks. That gun will also have the full set of subinspector's stamps on the requisite parts. A civilian Schofield will have non-cartouched stocks but can have various parts with sub inspector's stamps. For example, a subinspector may be inspecting cylinders. He creates two piles - approved and rejected. The rejected pile is probably very small. A fitter/assembler is building a civilian model and needs a cylinder. If the rejected pile happens to be empty, he uses a cylinder that has been approved for a military gun, so you will see civilian models with some parts having military approved stamps, but no military cartouche on the stocks.
Parson reported that he reviewed a "Day Book" at S&W that had 35 1st model ( if recall right ) Schofield shipments listed, w/o ser. #s. Those guns were for gifts and for some dealer shipments. That's why most references say there were 3035 1st models made and people incorrectly assumed that meant 3035 military models. I believe that total number, 3035, is correct, however serial numbers of actual 1st model military guns go from #1 to # 3000. Serial numbers from # 3001 to # 3035 are all 2nd model guns - so what were the extra 35 1st models ? It appears they must be the 35 guns on the unnumbered list Parson's reviewed and are the source of the 1st model civilian Schofields and it appears from examination of ser # 6 and 13 that those 35 guns were probably numbered 1 thru 35 in their own serial range. Ser # 6 is also stamped with S&W distributer's stamp for A. J. Plate. If the above analysis/asssumptions are correct, there must be duplicate serial #s for #s 1 to 35. A civilian #d gun & a military #d gun with identical ser. #s. So that's what I'm hoping to discover someday! I've owned or examined perhaps 1/2 doz + guns, with numbers under #36, over the last 50 yrs. Unfortunately only a few of them still had their original stocks (with or w/o a cartouche) and except for #6, none had a distributor's stamp. So, that's my story and I'm sticking to it!
Ed
PS: Both Petter & Mike are correct. Somewhere I have a list of the sub inspectors and if I find it, I'll post it here to show who "C" & "P" might be. The "P" is usually a proof mark, as Ordnance rules required that stamping, however there will be a subinspector's initial stamp also on Schofield cylinders, usually just under the serial number stamping, which also could be a "P" . ( I just took a look at ser. # 16 . It's military and the cylinder. has the subinspector's initial"L" ( for Lyle) under the ser. # "16" and the "P" stamp on the next chamber to the right of the Ser# & L stamp. Ser # 1 has the same stamping. Both are now Wells Fargo guns .)