After a long waiting period I received some 300MP to try, and while I am by no means ready to convert, the first results are very impressive.  Based on the results mentioned here at this forum and the burn rates, etc.  I  loaded 15 cases using 17.0 gr. and with Fed 150, 210M and Rem 9 1/2 primers.   The 17 gr of 300MP shoots to the same impact point at 100 yds. as my std load of 17.8 gr of 4759 with CCI 300 primer, and a BS 320 gr. Hoch bullet at 25:1 ratio.  Also the recoil is about the same.  I use a CPA 44 1/2, Badger 1:15 barrel, Unertl 20x scope.
The 4759 shot 1 1/4", 300MP and 150 primer 2 1/2", the 210M shot 3/4", and the Rem 9 1/2 shot 3 1/2".  The 210M group was nice and round and something to behold.  This was shot during a light steady rain with no wind.  A lot more work to do, but the weather here is not cooperating. An impressive first outing with this new powder. The next batch of cases is loaded and waiting.  Thanks to all those who alerted me to this powder.

The rain stopped and tried some more 300MP loads.   The velocity of the 17.0/300MP/210M load is 1270 fps. This compares to 1340 fps for my 17.8/4759/CCI 300 load.  Both with the 320 gr. Hoch bullet breech seated. Both shoot less than 1" groups for 5 shot at 100 yds. in  my CPA rifle.
An observation I made today is that The 4759 will shoot 3 shots into a ripped hole with two outside "flyers" to open the group, but all still within the one inch.  The 300MP, on the other hand, will put four into a ripped hole with one "flyer", all within one inch.  Weird what?  Perhaps just a tweak of .2 gr. may pull it all together?  The "flyers" have always been vertical.   Today I learned going less powder opens up the group, and the Rem 9 1/2 LRMag primers opened the group as well.
In any case, I have seen enough to take the 300MP load to our match next Sunday where we may be able to go 200 yds. weather permitting.