SU35,
The Nosler data uses the really old pressure standard for the .257 Roberts of around 45,000 CUP. In a 24" barrel it's pretty easy to get 3000 out of a 115, and no, this is not .25-06 speed.
Ok, true, but wouldn't you say the data used by Nosler is for the old 6.5x55 as well?
After all the x55 has pretty much the same water capacity of a 260 IMP which i know will get 2,900 mv shooting a 140.
Maybe it comes at higher pressure, I don't know.
I used a 140 A-Max in the Sierra program example because until your post, everybody had suggested the big advantage of the 6.5x55 lay in heavier, more ballistically efficient bullets, not bullets of the same approximate weight.
I knew that's what you were doing and I figured that I might as well show how flexible the 6.5 was by showing that it can shoot the same weight class of bullets of the 25 caliber but 6.5's for the most part have higher BC's in that weight class than the 25's and can be shot at the same speeds.
As the OP wanted to shoot chucks out to 1000.
There is no way in sam-hill a 257R is going to match up with a 6.5x55 in that category. (show me one 25 caliber rifle in long range competition and I'll show you 500 rifles in 6.5.) Not to mention that he will probably spend most of his time shooting chucks.
The 6.5's simply have to many bullet choices that out BC the 25 calibers , especially with a 123 MK in the 6.5.
On deer/lope at 200y take your pick.
On elk, I would rather take a 6.5x55 and yes I know you guys in Montana take elk with less including the 220 Swift of which is the only round a close friend of mine in Anaconda uses.
If you can tell the difference in effect between a .260 and .25-06, congratulations.
As I stated, at long range I do, with the lighter recoiling 260, thank you.
