As Dfariswheel wrote, P1s were for the military and for police use, P38s for civilian and police use. The slide has German BWB Abnahme stamps which were done by the military but also as a favor to police. However, often overruns ended up in the Bundeswehr arsenals. It has the Bw stamp which is the Bundeswehr property mark but the B seems to be thee wrong way?!
The gun was restamped with the serial numbers but they do not seem to match. For each lot of P1 there were non-serial numbered spare parts sent along. The parts used to rebuild this gun are used, so just put together from disfunctional guns that had been fired enough to lead to failure of some parts, those were usually the slide or the frame. It has the reinforced take down lever.
Because it appears that the gun was rebuilt by the military from used parts, while new parts were available, would make me shy away from this gun.