Magazine Springs for P-38, P-5 and P-5 compact are available in +5% and +10% extra power allowing a choice of springs for optimum magazine performance. The stronger spring is especially recommended when using extra power recoil springs.
My take on this is that if your P38 is functioning properly with your current magazines and springs, stay with what works. If not, then change according to the recommendations from WOLFF.
I use the +10% mag springs in my "shooter" P5 that has been fitted with a pair of 8# recoil springs (16# total). The standard P5 has 6# recoil springs (12# total).
This "shooter" P5 has 124gr/1200 fps ammo run thru it, and has yet to have any issues. I also regularly put my P5 Lang 6" barrel and slide on this 16# Recoil sprung frame, and shoot the 124/1200 ammo, zero issues.
I've found my 16# sprung frame will not function properly with a 30 Luger (aka 30 Para, aka 7.65 x 21) barrel and slide mounted, regardless of which # mag springs are used.
I have a 2nd "shooter" 12# sprung P5 frame for shooting 30 Luger, an ex DeutschBank Munich security gun.
Both of these shooter frames are 8th Variation (final). I really like the adjustable trigger stops on my shooter P5s.