Have received a Fwb P70FT action in 15J... It has a serial nbr. ' DE 500489' on the side of barrel breech, as well as the steel sleeve ...which after careful observation, seems to be a one piece barrel and NOT a sleeve. I thought this might be a barrel taken from a 10m, Running Target , or biathlon gun, BUT It has the proper groove rails at the top ??...it also has what seems like a subtle stamp mark at the bottom of the barrel breech, showing a ' T ' with a couple of ' V ' like arrows under it ...and a nbr. ' 08 ' Also, the barrel is so short - 51cm (20 Inches) from tip to tip - unusual ?