While the grip can be an issue,,, I want to ask you to look at this and evaluate it for your self. Consider backing off the excess powder load and go back to max load by the book, and give yourself a good crimp on these bullets. The start again at 50yd, then 100 and 150 or jump to 200.
Also have you do shooting at 50 and 100yds with this load? reason I ask is sometimes when a load is too hot for the bullet, The bullet begins to act erratic, and instead of groups you get flyers or a pattern.
I just feel that a good dose of AA1680 or some 4227 and a good crimp would help you out. A lot of Silhouette shooters have used that caliber for good success on Rams at 200yds. I use to have a 357 Max in a Ruger revolver and I used the 180 gr XTP and 4227 for accurate loads. A good friend just had to own it and he still uses the same loads.
I understand your reasoning on the No Crimp and heavy powder dose, but sometimes it simply does not work, especially for pistols. We do not have the luxury of nodes that rifle shooters do. Even some of our bullets have little or no BC.
YOu have chosen a good accurate bullet and I want to see you succeed with your Hunt.