USP EXPERT mainspring troubleshooting

[Lukas Koukal]

OK, so my mainspring died after some 35k rounds and uncountable dry-fire. I got new ones from Wolff - 10, 12 and 16lbs to try. The problem is, the gun only works with 16lbs one, I got 50% misfires with 12lbs one and no fire at all with 10lbs one. The trigger feel is noticeably heavier than with the old spring. What´s the original Match trigger mainspring weight? I always believed it was 10 or 12lbs, as 14lbs is standard in the ordinary USP. I ordered some springs from the factory and hope to get them soon, but still this puzzles me. Moreso, as I successfuly installed a shortened 10lbs spring into my P2kSK over a year ago and that one is still going strong after some 8k rounds, even now firing the rounds the Expert failed with. I see the FP is longer and thus heavier in the Expert, but is that what makes such a difference?

[razerface]

Did you take firing pin out and see how much dirt in there? Could be obstructed. 10lb spring should work if clean.

[Brian1979]

If your MS died after that long then how long has it been since you felt a fresh spring?

My point is that I dont think you remember how a fresh spring felt and its going to feel heavier to you now that you replaced it.

There should be enough roll pins floating around here now so perhaps you can score a couple and clean out the FP channel.

[Lukas Koukal]

FP channel clean, FP polished to mirror surface and both checked before this was posted. Wouldn´t ask were it that easy :) Maybe got "lucky" to buy a batch of weaker than rated springs...

As for the heavier feel: have enough guns to compare. And of course the 16lbs spring feels heavier, when something in between 12-14lbs is standard.

[razerface]

check your p/n again. sure they are correct springs?