Well, I'm going to find out tomorrow; just returned from a Gander Mtn where I purchased all but one of their tins of #11 MAGNUM caps, as well as ( and much to my surprise they had them on the shelf) T/C maxi-hunters-I went w/ the 275 gr in .50 as 350 gr seemed like a big hunk of lead to me...any sense of a good charge for these or would my standard PRB load of 75 gr 777 seem reasonable? I only have 40 of 'em so I've got to get it settled in pretty quickly.

Several years ago i bought the Winchester Triple Seven primers for use with 777 powder. They did not reduce the crud ring and i set them aside. Later tried those caps with 2F Goex Pinnacle. They gave inconsistent ignition with Pinnacle; this caused vertical stringing of my groups. Gave away the the remainder of those primers.

Yes, it was the caps which made such a difference. The #11 mags I purchased yesterday had me hitting right where I was previously w/ the same PRB & load. I presume the ignition of the charge was "weak" and therefore the entire oomph of the 75gr may not have been delivered.(?) Would not believe it if I had not experienced it myself.

Next, as you all know, the maxi-hunters do not shoot well out of the 1:48 T/C...I had confused maxi-balls/hunters in my mind. I was just excited to see traditional supplies on the shelf at all.
They hit low by one full revolution +1 click on the rear sight. Even then not a good group, so I used a patch on top of the charge which seemed to tighten them up (have no wads,etc) as well as tapping the perimeter of the base w/ a small hammer to enlarge it a bit. Frankly, I don't think that made a bit of difference and these simply do not seem to engage the rifling adequately.
Ultimately I was running out of sight adjustment & they still were hitting low. Perhaps by increasing the powder charge I could have remedied this but a) I do not feel confident enough to hunt w/ these & b) the PRB was right on the money out to 80yds.

So, I've got one full box of 275gr maxi hunters if anyone wants to trade for round balls, etc.