I picked my son up one of those new Rem SPS rifles in 30-06. It is supposed to hold four in the magazine. If I put more than 2 in it the cartridges simply pop up and nothing will feed. I swapped the follower and the spring with the one in my Rem 700 30-06 and nothing changed.
Any suggestions before I ship it off to a Remington authorized gunsmith to have it fixed?

Check and see if the mag is assembled correctly.

If the mag box isn't centered under the feed rails properly, it can allow the sheels to "geyser" like you describe. You can probably just open the bolt and feel around or just take it apart and reassemble it, making sure everything is right.

In all my years with Remington rifles I've only had it happen once, but it can make you wonder WTF! when it happens.

If its a BDL loosen the guard screws and open the floor plate. Reach in with your fingers and pinch the rear of the mag box together and work it up and into its recess in the bottom of the receiver, making sure you get the front and the rear up in there. Then tighten the screws back down and check to see if it works.

If its an ADL the mag box is screwed to the receiver with one small screw and you’ll have to pull the barreled action out to check for tightness of the screw.

You guys are good. I thought I had made sure the floorplate was in fully but it wasn't. I knew there was a gap where the floorplate wasnt seating flush but I didnt pay much attention to it. I took it apart and reinstalled it and now it functions perfectly. Thank you.