I've used the XTP 180 gr., the Rem. 180 gr. jhp, Nosler 180, and more recently the Hornady SSPB.
In my 12.5 in. MGM encore barrel the SSPB is most accurate and that is with 26.5 gr. of 1680 powder. I have also used H110 and N120 with xtp's and rem.
They all shoot/group good, they just have different points of impact.
I have shot the Rems and xtps at 200 yards and for me and my abilities I was very satisfied(3-4" 3 shot groups) I did have 2-- 1 1/2 " groups with n120 with xtp's. (Finally got a shipment in so I will look at this load in the future)
I spoke to one of the techs at Hornady about the SSPB and asked at what minimum speed it would still expand-he said 1400 fps. With the rifles in 357 max that is not a problem. With the encore pistol that is about 160-200 yards with 1680(based on listed velocities, shorter barrel and sierra suite calculations)
Here are a few links with much better information than I have.
http://357maximum.com/developing-a-load/http://www.bellmtcs.com/store/index.php?cid=121http://www.lasc.us/Fryxell357Max.htmhttp://www.lapua.com/index.php?id=1195http://www.accuratepowder.com/loaddata_caliber_handgun_standard_357cal.htm