You need to squeeze the magazine to get one of the tabs out of the action slot.
I've heard of people using a c-clamp to squeeze just enough for the tab to clear without warping the magazine.
I use a spare Savage recoil lug. Screw the front screw into the action. Wedge the lug between the screw and the magazine. Use the palm of your hand to force the lug between the two. That should be the perfect amount to clear the tab from the slot.
Now, getting that thing back in isn't easy either. Get the biggest flat blade screwdriver you can find. Prop the barreled action up against something soft. I use the sofa with the tang resting on a magazine or newspaper. Put the rear tab in the rear slot. Put the screwdriver in the crook of the magazine tab and apply a bit of pressure. Whack the handle of the screwdriver with the palm of your hand. The tab should pop into the slot.
Both of these maneuvers may take a couple practice runs, but they are cheap and work good for me.