Here's more or less, "the standard" on the P1.
First, the P1 is nothing more than the military issue version of the POST-WAR aluminum framed P-38.
100% of parts interchange, since they are in fact the same gun.
Some later P1's had reinforcement pins in the frame and a beefed-up slide, but the gun is the same.
NEVER shoot hot ammo in the P-38/P1.
These were designed for use with standard load 125 grain, full metal jacket ammo.
You can shoot 115 grain ammo, and most guns will handle defense type ammo if you're willing to experiment until you find a brand/type that will feed reliably.
They were NOT designed to shoot either hot ammo, or heavier bullets.
Doing either will damage the gun sooner or later.
NEVER install "extra power" recoil springs.
Two things can cause the slide or frame to crack.
One is hot ammo, the other is stronger springs.
Stronger springs may "pad" the gun when shooting hot ammo, but the slide slams SHUT with much greater force, and this will cause the frame to crack through the dismounting lever hole as the heavy springs literally hammer the frame forward.
NEVER attempt to move the rear sight.
The rear sight is NOT movable for windage, and attempting to move it will destroy the top cover.
All windage adjustments are done by moving the FRONT sight.
For elevation, buy a higher or lower front sight from Earl's Walther Service.
Don't remove the top cover unless you absolutely have no choice.
The cover is easy to spring or mis-install, and this will allow the cover to blow off under recoil, scattering internal slide parts far and wide.
Reliability is usually good with the ammo it was designed to shoot.
It is NOT a target pistol, it was made for military use.
Reliability is a factor of the ammo, and whether you clean and lube the gun AND magazines. Some guns and mags have never been cleaned and may be full of dried storage lube.
The P-38/P1 has a history of throwing brass into your face. This is a "feature" of the odd left hand ejection.
The trigger pull is heavy and there's nothing to do about it.
Lighter springs almost always cause reliability problems.
Quality of the gun is sky-high.
Walther is the premier European gun maker, and the P-38/P1 was their top-of-the-line model for years.
As such, these current import P1's are very much a "best buy".