The fist specimen is the normal/current headstamp used by PMP. It is the same for the normal PMP and ProAmm loads, as well as the relatively new Kalahari Elite, which is loaded with Swift Scirocco 100gr. bullet
The second specimen with the blue base stripe is a normal ProAmm and is marked as such when it is given to shooters at the ProAmm shoots. The shooter receives 3 rounds to shoot the tightest possible group with normal factory loads. The current record is with a 30-06 with a grouping of 1,80mm. Pretty fancy for factory loads.
The third round I am not too sure about. It has a blue base together with a red base stripe. The assumption is that it is a proof load.