Some people report problems with the DM models of the PSS line.
Many others take those reports and do the internet multiplication thing.
The DM LTR was discontinued.
It's a PSS with a 20" fluted barrel instead of the 24" or 26" non flute barrel.
It's a heavy barrel and they don't heat up fast at all.
For the record the magazine on my 300wm PSS DM that passed through many peoples hands before it go to me works perfectly.
If you have a DM that's acting up there are two things to check
1)If the slots in the bottom metal are too open, the mag will sag in the rear and the bolt won't pick up a round. To fix you just use a punch and hammer to close them up until the mag sits flush with the bottom.
2) If the rifle is bedded or the stock too think the reciever sits too high from the bottom metal and the bolt can't pick up the round. Removing material so the receiver sits low enough cures the problem.