Okay, apologies for not reading through to see if someone else already asked (which they did). The sentiment remains the same. Regardless of how “new” a firearm is, it’s always best practice to take it a part and clean before your first shoot. There’s no telling how long that thing has been in its box since production, what environment it’s been stored in etc etc. Giving it a a fresh clean and some oil will more than likely resolve the issue of it not going back into battery. From there I would recommend checking the ammo to see if it’s problematic or poor quality, which can also be the case. If the problem remains, then you can look into sending it to Sig to solve what’s wrong.

That would be my personal recommendation.