The 6 rd mag on my brand new 290RS will not eject when fully loaded unless I first push in rather hard on the floor plate and then pull it out manually while holding the mag release button down. It ejects properly if it is empty. The 8 rd mag works as it should both full and empty. I don't see any difference in the slots in the mags and the mag button is releasing fully when I look down the mag well. Anyone else have this problem?

Does it do this after you cycle a round into the chamber or will it still do this when just inserting a full magazine with the chamber empty...

I mention this as sometimes...after clambering a round in a full magazine...the second round in the magazine has moved slightly forward blocking or at least causing some issue with ejecting the still full or one round down magazine.

Strong springs and should not be an issue.

Good luck with you P290

Bill

I owned a P290RS and I'll say that the mags seemed generally crappy. Sharp edges and the top round liable to pop out at the slightest jostle.

After playing with the small mag for a while and really forcing the mag release button, it started ejecting but with above normal force on the button (takes both hands). I think I'll keep doing this to break it in and wait on my first range time before I talk to Sig. I did find that the top round on both mags will flop around unless you push it down into the next round to make it square up with the lips of the mag. If you just push down with a loader and push it to the back of the mag, it does not seat properly. After it seats properly it doesn't move.

Don't own a P290rs, but had similar issue with a P6 years ago.
Are there any marks on the side of the magazine, like it's scraping against something inside the magwell?
Wonder if sanding the inner walls of the magwell polymer would help. Of course, I wouldn't do that without exhausting my options with Sig first.