Chassepot - the SB headstamp also exists as 19 / SB / 26 / P. Note: The dot after the “P” IS ON the headstamp. There is a vaiant headstamp, with no dividing lines: 19 SB 25 2. Note that the “P” for Prague is replaced by the number “2” which is probably the month the case was produced.
All of your rounds except the 19 P 02 M are generally considered as 7.63 Mauser rounds. Most sources show the Polte round as a 7.65 Mannlicher. I suppose someone, somewhere has a box label for it, but in truth, I have never seen any documentation that proves it is a Mannlicher, although in storage of my variants in my collection I adhere to the common wisdom. It exists in a number of minor variations in FMJ CNCS Ball, having to do with mostly changes in the thickness of the rim and the width of the extractor groove and the extractor-groove bevel. I also have the SN bullet with what looks like a steel ball in the nose. I don’t know what the Germans called this bullet. It is similar in concept to the American Hoxie bullet, but not identical in construction, it would seem. I also have a nickeled dummy round with this headstamp, which has the addition of a knurled cannelure around the middle of the case. There are enough variations, all marked “02” for a date, that I am almost inclined to believe that is a Model Date rather than the date the cases were made. That, too, is without documentation however.
IN the Spandau round, I have one with a CNCS RN SN bullet headstamped S 11 02. I also have a Purple-wood bullet blank with orange-red primer seal and a knurled cannelure around the case about 1/3 of the way up from the head. It is headstamped S 1 98. The color of the seal and the cannelure are identical to a Model 88 7.9 x 57 blank I had from Spandau, with an “89” date.
Oddly, I have never been able to find a FMJ bullet loading of this round for my own collection, and yet overall, that seems to be the most common form of this very scarce cartridge.
You picked up a very, very nice group of 7.63s there!