[threefeathers]

anything but Federal 135 grain P Def and Magtech ball. Everything else jams 3/4th the way in. I have used 4 new Sig Mags and all do the same thing.

[Old Fuff]

Have someone check and see if the extractor is binding because of dirt or fouling in the hole behind the extractor that holds the extractor spring and plunger. This is an area that should be kept clean and often isn't.

Also, SIG's seem to love lubricant. be sure the slide rails and the lug on the bottom of the barrel are oiled or lightly greased.

If all else fails it should to back to SIG (with the magazines) to determine exactly what is wrong.