Not sure why you picked the #11 charge, Deano, because the OCW method says you have to have three compatible charges in order to have a node or sweet spot. On those last test groups you shot, you didn't include the charge that would have been the next one down from #11.
My guess is that you decided to test #11 some more because that's what you saw as the smallest group of the bunch, even though it was only two shots. This happens to a lot of us when we first start tinkering with the OCW method; we just can't tear ourselves away from that one really great group, even though the charge weights on either side produced much larger groups.
You've got to remember that the #1 goal of OCW is to find three powder charge weights that result in the tightest/least amount of vertical in the rounds fired. That's the whole goal. If I shoot 10-12 charge weights and there simply is no discernible node, then I try other powders or a different bullet. We all know that there are guns that just don't like a particular weight or style of bullet; same for powders, although less often. I have a Remmy in .243 that prefers Remington brass over any other. It's the only gun I have that's that way, but I've tested it over and over and it's simply a fact. I suspect it has something to do with case volume and I could probably play around with the powder charge and get it to shoot Win brass well, but why go to all that effort when I already know it shoots really, really well with Rem brass and my favorite .243 hunting bullet and powder.
I went back, looked at the last groups you fired and realized I misread the targets. See how you have some bullet holes that show up both on the upper target AND on the lower, where the paper overlapped? Dummy me didn't realize that's what was going on and I thought those were different holes. Looking at the targets again, I really like similar vertical and velocities in the last three groups. Carefully load 13 rounds at 45.4gr, using the SAME jump as you did on the target you posted. Take 'em to the range and shoot 3 fouling rounds from that batch of 13 you loaded, then shoot two five-shot groups at 300 yards. Make sure you have flags out and don't get in a hurry. Pick a condition and don't pull the trigger until you have that condition. Don't worry about some time limit, you don't have one. You want the absolute best 5-shot groups you can produce. My guess is that if you're careful, you may well end up with two groups both 1 1/2 inches or less, which is .5MOA. I forget what rifle you're shooting, but if you can shoot .5MOA at 300 yards, that's pretty incredible in most people's books. Give that a try and see what happens.