I suppose the very cold temperature might have made a difference at first, but after a magazine was fired, the gun should have been at a reasonable temperature. The 115-grain bullets may be the problem. If it were mine, I'd look the thing over very carefully for damage to the frame, chamber or barrel, and if none is found, I'd try different brands and weights of cartridges. I don't think you should use any "Plus P" loads in that gun, but 124-grain loads might help. There's so much different handgun ammunition -- especially 9mm -- that it's really hard to know what will work best without just trying different loads. Also, early P-1s were made like the P-38s, but with an aluminum alloy frame. Sometimes cracks showed up in the frame in heavily used guns, and Walther introduced the hexagonal pin behind the locking block in later P-1s and the P-4s to protect the frame. If your gun doesn't have that pin (mine is one of the Manurhin-made P-1s and doesn't have it), you probably should look at the frame, just to be sure. Most likely, the type of ammunition is the problem.
