pps-43 preload springs

[inch man]

A lot of people have a problem with the 7.62 tokarev cases shoulder blowing foward a bit after firing. What I did to fix this was to preload the recoil spring. I had some 1/4" leather that I cut 4 pieces to the dimension of the plate on the back of the recoil assembly, glued them together, and placed it behind the assembly. Made it about 1" shorter that the spring would compress. The factory spring has an initial pull of 4.2 lbs. The pre loaded spring is 6lbs. This allows the bolt to stay closed just a bit longer, thus reducing the case shoulder lengthening. Takes one's mind off of the "firing out of battery syndrome".

[Stickman]

Nice, I used to play around with a PPSH a long time ago.

[Zeeba]

I read with great interest about this fix-it for the PPS-43's habit of blowing case necks out. My question is, how is the spring holding up with its compression distance shortened by an inch? I want to try this with my pistol, but I'm leery that I might be wrecking the spring in the process.
The picture below illustrates the various results of firing my '43 with commercial S&B ammo:
http://img.photobucket.com/albums/v156/FlyerTom/Forum%20Uploads/DSC00016.jpg
As you can see, the second and third cases from the right have no necks at all and I am most concerned about this from both a reloading and a safety standpoint.

[Zeeba]

I read this thread with great interest as my PPS-43 exhibits the same habit of blowing out case necks.
My question to you is, how is the recoil spring holding up with its compression distance shortened by an inch? I'd like to try this fix-it myself, but I'm leery that I may wreck the spring.
The picture below illustrates some of the results of firing commercial S&B ammo:

http://img.photobucket.com/albums/v156/FlyerTom/Forum%20Uploads/DSC00016.jpg

As you can see by the second and third cases from the right, they have no necks at all. I'm most concerned about this issue from both a reloading and safety standpoint.