Sigs are notorious for that. I would check first if it isn't in fact your thumb causing the issue (Sigs are notorious for having bad thumbs riding the slide lock, preventing the slide from locking back on an empty mag during fire). If your thumb turns out to be the issue, which is more than likely, I would contact the vendor who sold you that thumb and ask for a replacement.
SIG P226R slide not locking back after last round
- Thread starter Brucy
- Start date
Federal AE 124gr
A pal gave me a really good deal on a P226-40...the slide would never lock back on an empty mag [Sig marked, plastic floorplate]. I acquired some Meg-Gar mags [Italian made, thin steel floorplate] and the slide locks back every time with the Mec-Gars. I don't mean to say that this must be the source of your problem, but trying a different style of mags might help you if the other ideas don't pan out.
I have 3 mecgar mags. Same issue. Will know this weekend if its user error!
True it is very easy to do. The natural thumb position for a 1911 is almost certainly a guarantee that the thumb will press in the Sig slide release. Been there done that but I also have one mag that is not holding open and one that does. A mag issue. I mostly use reloads and I have found the Sig to be very forgiving when it comes to the oomp of bullet. The most forgiving of all my guns. I have loaded from well below minimum to full power loads with no hold open issues. This forgiving nature of the sig is one of the things I really like about it.
