Looking in my Lyman 49 manual had no help for your Barnes bullet, but I did see something that might be interesting: That manual has data for .43 Mag* in both rifle and handgun length barrels. For both 225 gr and 240 gr jacketed, the gap between 4227 and Unique got larger in the rifle (about 300 FPS difference in rifle), but the gap between 4227 and H110 got smaller, going from about 200 FPS in the handgun to a little under 100 FPS in rifle, on average.
That suggests to me that in addition to being a very safe powder in .43 Mag, 4227 is more suited to your rifle than a hangun. This makes sense, as it's pretty much the slowest-burning powder you can use in a handgun cartridge. When fired in my revolvers, I always find partially burned grains of 4227. It would be interesting to see if that goes away in a rifle.
The other nice things about 4227 are A. nobody wants it, so it's the last powder to disappear during a component panic and B. it seems to be very gentle on the bullets. I had a bag of RMR plated 240 grain bullets that shot not great but OK over a full load of 4227, but looked like I'd been firing buckshot when using a load of Longshot that, by the book, should have produced at most a similar velocity. My guess was that the faster burning powder was causing them to hit the rifling harder and tearing up the plating.
*To explain this: Not a typo. Some joking-not-joking honesty on my part, since some .45 Colt guys get SO excited about the 23 thousandths difference between .44 Magnum and .45 Colt bullets. ;^)