this is what I found in my short search after I bought my P1 which is the older version no pin, thin slide.
from P38 forum
http://forums.p38forum.com/forums/viewtopic.php?t=13142
After reading it I decided to just replace springs and keep my loadings in the 115gr @ 1100 fps range. I really enjoy shooting it and have had no problems with FMJ ammo. I can tell you that UMC 115 JHPs don't work at all the front of the bullet is too short/fat and recoil wedges it where the mag overlaps where it's welded.