I have used 1000s of 300 grnrs in 44 RM and Super Blackhawks, I started loading them way back when the only maker was Barnes for the 444 Marlin. I have used exclusively Win 296 powder and CCI 350 mag primers in W-W cases. I actually trim all my cases to book min then load and do a heavy roll crimp into the cannelure, never worried about COAL, just used the cannelure on all the different makes of bullets. I worked up well beyond book max but they are a good guideline and you do not want to start above them. The 300 gn Barnes were the most accurate bullet I ever used in my 44s, in conjunction with Win 296 and magnum primers. She's a handful though with a full bore, fire breathing, magnum load............
Start about 20 grains and work up in 1/2 gn increments...........pistols are different than rifles so forget looking at primers......as long as your cases drop out or fall out with a light tap all is good, any harder than this and it's time to back off......