Most of us prepare for worst-case scanarios, and we should include possible murder prosecutions in our List of Worst-Case scenarios. Your local prosecutor may or may not use every trick in the book to hang you, but you need to prepare as though he absolutely will.
With that said, there are very good reasons to use that spring, and you've already shown that you can articulate a reason for doing so:
RobertSB701 said:
. . . . I performed the typical (yes I messed w/ Perfection) rubbing on rough edges of my Glock's inner workings resulting in a smoother trigger. I would like to do the same to either carry pistol along with installing NY1 trigger spring for a preferred heavier, more consistent pull. I tried the NY1 spring in my G-21SF and liked the resulting trigger. . . . .
Now just put some thought into
why you prefer the heavier, more consistent trigger pull. At the risk of sounding like a lawyer
D), you'll need to figure out how to make a jury (which may not be very gun-savvy), understand that your modifications make you a safer shooter, not a more dangerous one. There's always a risk when a CC'er starts monkeying around with his equipment, either in the gun, or his ammo. The major difference with gun modifications as compared to ammo (read "handloads"), from a trial perspective, is that the gun is not destroyed in the shooting, so it will be available for testing by the State's, and your, experts. The usual pitfall in pistol modifications is when someone lightens the trigger pull, then wants to claim that the shooting was accidental. The pitfall here is that, should you ever try to claim that a shooting was an accident, a heavier trigger is easily portrayed as making an accident even more unlikely. Other than that, I don't really see a problem with making mods for a heavier, more consistent trigger pull.
From a possible trial perspective, I would simply add one more bit of caution.
arentol said:
. . . .Besides, all your lawyer has to do if the prosecutor start looking down that path is subpoena (or just hint he will) the local precincts armorer who will either have to perjure himself or admit he has smoothed parts on guns and replaced springs himself. That will get that whole thing shot down in a no time and it will never be mentioned in court.
This is in no way a bad idea, but I would not count on it. If your lawyer tries to subpoena the police armorer, the prosecutor will likely object on relevance grounds. If he wins that argument, it won't matter what the armorer does, because he won't get to talk about it at trial. OTOH, if the armorer does the same thing that NY does, and you've installed a spring developed (or inspired, as Tom put it) by the NYPD, your lawyer has a decent shot of beating the PA on relevance.