Mine both do well with the BT's. Never tried the HB's or FB's. At one point, I was loading with 46gr 4064 and that also did very well in my rifles. FWIW, I also use these same loads in my M77 MkII and it does just fine at 600 yards.I love shooting mine too! Your load is basically same load i use except i use 49gr of 4064 and i use 2130 sierra bullets(gameking i think). Mine didn't like BT's as much as the flat base for some reason.
One of my rifles is in great condition, very low serial number and from what I can tell, it is all original, matching serial numbers, at least, the ones I've checked so far. I baby it, but it's no safe queen and it shoots well. I'll never do anything more than basic maintenance on it. If, by some miracle, I'm able to shoot it enough to wear it out, I'll retire it for my own sentiment. From the looks of it, I'm of the belief that it's seen some battles.I contacted “The Garand Guy” and his shop is about 45 minutes away from me. For $200 he will put a new Criterian barrel and headspace it. I think I may have him do it over the winter. Other than that my rifle is match ready. The barrel that’s on it is good but the bore is dark. As a informal shooter it’s fine but I’d like it to be the best it can be. I was thinking about one of those adjustable gas valves so I can shoot commercial ammo. There’s some good match stuff from Hornaday and others.