38 Super magazine identification

[jhota]

Recently picked up a used Para Ordnance SSP in .38 Super at the local pawn shop. Got a decent deal on it, but I am trying to identify the magazine that came with it to decide if it's worth trying to fix it. The only other mag I have for this gun right now is a CMC Power Mag. I expect I'll just buy a bunch of those, assuming the gun runs ok, but I am curious about this thing. Drops free, but does not lock the slide back. The McCormick mag does. No idea what the mark on the floorplate is.

https://i.imgur.com/6zMpNgE.jpg

https://i.imgur.com/cpPmm8R.jpg

Any thoughts?

[Doran]

That M symbol represents Metalform.

https://metalform.us/about/

https://gunmagwarehouse.com/brands/metalform

[Jim Watson]

Yup, Metalform.
That "fully skirted" follower is usually very good about lifting the slide stop, I don't know why yours won't.

[Hawkmoon]

Yes, definitely Metalform. As Jim Watson posted, that follower should lift the slide stop. Check to be sure the slide stop moves freely, then check if the magazine spring may be weak.