It appears that the question regarding Apex spring kits for J frames was answered above, but not quite directly. To attempt a more direct answer, there is good reason for concern on a gun that is capable of being cocked, since the single action trigger pull would also be lightened. However, on a gun capable of only double action, the resulting trigger will still be long and heavy enough so that a credible allegation that the modification was unsafe cannot be made.
I have only one gun with a professional trigger job: a North American Arms .380. That gun is DAO, and the trigger is still long and reasonably heavy. My accuracy was significantly increased after the work. I carried this gun daily for several years, and would not hesitate to do so again.
While I would never recommend a Glock with a minus connector and standard trigger spring, my Glocks have minus connectors with NY1 trigger springs. One of them is carried daily in this configuration, and I am aware from Glocks own publications that they have supplied guns with this configuration to various police departments.
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