Er... not one of you has brought up the Ross? If you read McBride (A Rifleman Went to War) and a bunch of other WW1-vintage primary sources, then the Ross rifle ranks at the top of the accuracy food chain c. Great War. But then again, I don't have any modern data to back this up. But the Ross rifles with Winchester or Warner Swasey scopes were in high-demand for the Great War sniper crowd.
I would also add, by way of full-disclosure, that Sir Charles Henry Augustus Frederick Lockhart Ross, 9th Baronet was my great uncle (mother's side). So I am utterly prejudiced. It also makes me extra snobby if you want to run with my profile. I have a couple of Ross rifles. One handed down. Another from Gunbroker. They are neat pieces. One of these days, I will get around to buying one of the Ross sporting rifles... they are really nice pieces of kit.
Just something to think about. Because when the Ross Rifles weren't blowing bolts back into the faces of troops (due to bad bolt assembly... which stemmed from poor non-private-proof design) they were super accurate.
Cheers,
Sirhr, the snobby indirect scion of Sir Ross, the family nutball.
PS... in the family, "The Baronet" was known as "Crazy Uncle Ross." I refer to him as "my hero."