Some semi-auto DAO only guns can recock/release the internal hammer/striker without the requirement of having the slide cycle to recock. If you experience a failure-to-fire due to a light strike on a primer, this might help you. (My old Kel Tec P11 was like this.)
Some will only recock/preload-the-striker after the slide has cycled. My Glock 17 is this way.
2nd strike capability is not on top of my list of reasons to buy a specific model. With a failure-to-fire, I would prefer the muscle-memory-method of clearing the round to potentially be a blanket solution for many problems.
I'm with p_m. If the round doesn't fire, I'd rather have a different one in the chamber for the next trigger pull. Why would I want to give a second chance to a cartridge that I'm pretty sure is bad?
"2nd strike capability" has been around for years on DA autos, but somebody thought it would be a good marketing ploy to turn it into a "feature", saying you could save precious seconds. I disagree; it's a time WASTER.
When training you train to do one thing when a round doesn't fire... tap, rack, bang.
With second strike "feature" you'll now have to wonder in the heat of the moment, "well was it a light strike, or a dud primer, a jam, or did it not go into battery, or... hmmm.... should I pull the trigger again, or try to clear it, or ..." Too late.
Well, the idea is due to some research that someone did a few years back. According to them, if you pull the trigger on a functional gun, and the bullet doesn't fire, 85%(maybe even more, but I am sure the figure I saw quoted said it was in the mid or upper 80% range) of the time the bullet will fire with a second strike. I like the feature, as I could obviously pull the trigger a second time quicker than racking the slide, but it isn't that big of an issue. I think out of the 10,000+ rounds I have fired in my lifetime, I may have had one or two "duds." However, I know that at least one of them did fire the second time, I remember that for some reason.
Of the duds I have seen (so far, hundreds working at a range), "strike two" is strike three, four and five in my book. From what I have seen with duds, generally, if it doesn't go off the first time, one is wasting time clicking away at the bad guy while they kill my family or me. Bang, click, tap rack, dont sit there and click at them like a cricket...
I agree that the second strike capability is a useless feature. If a round does not fire the first time. Then either the round is defective, or the gun is defective. Personally I would want to clear that round, and chamber a fresh round. Not rely on it to ignite on the second attempt. My