I just went through this with obtaining the same chambering in a Blaser K95 barrel. Both the K95 and the Merkel are chambered for other high intensity loads so I was completely surprised when Blaser USA told me to stick to 7x57R factory loads or similar handloads. IIRC, they boot a 140-gr bullet at about 2600 fps, or about 200 fps under a modern 7x57 rimless in a strong bolt action.
All I can think of is they are thinking liability in all this for some reason. Long story short, found my K95 has a very long throat so I can seat the 139-gr Hornady Interlock out so far there is barely any shank left in the case. Anyway, I'm starting with R17 and 46 grains and working up as far as I can go maxing at 50 under this bullet (if I get that far). I'm not saying this is safe in my rifle let alone yours but I am betting it is.
BTW, I passed this by John Barsness who also has a Merkel in 308 and he too felt they were hedging because of liability issues. Again, I can't really understand this for a rifle with an action handling the 300 Win Mag and assorted other high intensity cartridges.
Additionly, my barrel is not old but manufactored in the last coule years, so age isn't an issue either.
Best of luck and keep me in the loop with your findings.
George
Last edited by George_De_Vries_3rd; 02/25/13.
