To me the M1903 Mannlicher-Schoenauer is the ultimate. In fact I found a dandy one a couple days ago and like a fool walked away. I shall correct that on Monday. Thanks for the impetus.
I've owned a couple and regret letting them go. Time to correct that. Been doing a lot of that of late.
You've forgotten more about the 1903 MS than I will ever know...but I did discover something regarding the bore dimension discrepancies. A lot of guys, including myself, tried .266 ish Carcano dimensioned bullets (usually without much improvement or joy). I gave up and used some Nosler Partitions, got better results but not quite what I had hoped. A friend gave me a bag of Privi Partizan 156 semi round noses, the most unlikely charge of 39 gr of the much unloved H380 in Norma cases. Bingo, a 3 moa rifle shrinks to about 1.3, at a very respectable 2,340 fps. It's worth a try if you are disappointed in the results of more traditional load recipes.
I remember reading a Ken Waters article ( "Pet Loads") about the 6.5x54 M-S 1903. Accuracy wasn't great with great with "normally available" jacketed bullets which had 0.266" diameter (3 moa?) Waters slugged his 1903 M-S test rifle, and got a groove diameter of 0.268" ( 0 .002" larger than anticipated) . He order some 160 grain round nose jacketed bullets that were 0.268" diameter (Barnes original? ). His accuracy improved immediately to - I believe- ~1.5 inches at 100 yards. fwiw.
