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.
I read his piece in Pet Loads, which prompted me to try the now-discontinued Hornady .268 Carcano bullets. The experience wasn’t quite so productive. One issue was was with the neck diameter of the loaded cartridge. All of my cases are recently manufactured Norma, which have thick neck walls, probably thicker than the stuff that Ken Waters used and almost certainly more than cases made in the early 1900s. When seating the .268 bullet, the neck diameter was right at the min chamber spec for the 6.5x54. In my rifle, some cartridges would chamber, others would not. While neck turning was an option, rifle’s throat was also less than ideal for the combination. The blunt profile of the Hornady RN combined with he larger bullet diameter required very deep seating. Not only did the loaded cartridges look awful, they also wouldn’t feed worth a hoot from the finicky Shoenauer magazine.
So I quickly abandoned the effort. Just never felt it worthwhile as acceptable accuracy can be found with .264 bullets, particularly the Hawk 160s.
