How does the mechanism of the Sig Sauer SRT differ from stock?

[GetmeoutaCT]

Hello all -

First, I understand what the SRT does; I have a few of these kits installed on my Sigs and enjoy what they do. I'm not posting this to discuss the pros and cons of the system.

What I am interested in learning is exactly how the SRT kit affects the mechanisms of the single- and double-action trigger pulls. I know that the SRT sear has a protrusion that replaces a protrusion on the stock trigger safety, and that the SRT trigger safety has no protrusion but a longer "tail." What I would like to know is now these new parts interact with the rest of the internals. I also am curious as to whether the installation of the SRT kit eliminates or otherwise modifies any of the stock pistol's mechanical safeties.

Apologies if this has been asked and answered previously; however, I cannot find any such thread. There seem to be many threads on "SRT - good or bad" or "SRT - yes or no?" but none I can find answering my specific questions. Thanks very much-

 

[1KPerDay]

It doesn't affect the DA pull or the mechanical safeties. As for the rest you'll have to wait for someone smarter than I.

 

[1KPerDay]

some reading but still doesn't actually discuss the mechanism, just the effects.

https://www.thehighroad.org/index.php?threads/sig-sauer-short-reset-trigger-srt.548947/

 

[9mmepiphany]

It doesn't affect the DA pull or the mechanical safeties.

Yes and No.

Yes: The SRT mechanism has no effect on the DA pull because it only shortens the reset of the SA trigger

No: The SRT does not allow the Firing Pin Block to reset (block the firing pin from moving forward) between shots if you are releasing the trigger to the shortened reset point...it bypasses that safety. That is why, early versions of the SRT equipped pistols doubled when they were first introduced for a LE contract (to compete with the 3rd Gen S&W). SIG increased the engagement between the hammer and sear to prevent this...which resulted in a somewhat heavier release

There are other designs available (Grayguns) which allow the FPS to function between SA shots, however SIG's design does not.

 

[1KPerDay]

if I'm holding the trigger rearward far enough to disengage the FPS why do I need the FPS again? If I drop the gun I let go of the trigger and the FPS engages, right?

 

[9mmepiphany]

if I'm holding the trigger rearward far enough to disengage the FPS why do I need the FPS again?

The difference is that you aren't. The non-SRT FPS is engaged as the slide moves to the rear and the firing pin is drawn back by it's spring. It is engaged as the slide pushed the barrel into lockup and the round is chambered.

The SRT doesn't let the FPS re-engage to prevent the gun from doubling should the sear/hammer engagement fail

 

[GetmeoutaCT]

Thanks all; it was my understanding that the SRT effects the safety somehow.

Question - if the hammer is decocked after firing so that the pistol is now double action, will this re-set the FPS? Based on the discussion above, I suspect not.

 

[1KPerDay]

why would you suspect not?

 

[JTQ]

Question - if the hammer is decocked after firing so that the pistol is now double action, will this re-set the FPS? Based on the discussion above, I suspect not.

Are you using the decocker? If using the decocker, I'd expect the firing pin safety to be reset. As 1KPerDay asks, why would you suspect not?

 

[9mmepiphany]

The FPS is re-enaged when you release the trigger

 

[GetmeoutaCT]

why would you suspect not?

Because as stated above, it is the movement of the slide rearward after firing that resets the FPS, but not if the SRT kit is installed. Therefore, if a shot is fired and then the hammer is decocked, nothing has been done to reset the FPS. In fact, if I understand correctly (which may not be the case; hence my original question), it sounds like installing the SRT kit might permanently disengage the FPS. If that's not right; apologies again.

 

[9mmepiphany]

if the hammer is decocked after firing so that the pistol is now double action

if a shot is fired and then the hammer is decocked...it sounds like installing the SRT kit might permanently disengage the FPS

The FPS is re-engaged when you release the trigger.

If you haven't released the trigger, the trigger mechanism wouldn't be in DA. It also wouldn't be resting on the FP as the de-cocker doesn't lower the hammer that far