There is one issue that needs to be cleared up.
This may have been a mis-statement:
The SN >IN FRONT< of the rear flip sight is 115182
M1 Carbines had the serial number stamped BEHIND the rear sight.
The only Carbines that had numbers stamped in front of the rear sight were Carbines that had the adjustable sight added as part of a rebuild.
Since the adjustable rear sight over hung the area where the serial number was stamped, on some Carbines the serial number couldn't be read, so Ordnance re-stamped the serial number in front of the sight.
Ordnance manuals show the special stamping fixture that was used to re-stamp the number.
A re-stamped serial would have been done only on a late to post-war Carbine rebuild.
There would be no chance that a paratrooper Carbine would have had an adjustable sight installed, the number re-stamped in front of the sight, then had the adjustable sight removed and an original flip type sight re-installed.