Strud34,
6SM brass can be obtained in the UK but by special order and considerable expense - it's German made by RWS and would have to be specially ordered through RUAG Ammotech (UK). You'd likely wait months and pay £1.50 or £2 per case.
There is little benefit if any though in 6SM over 6XC except for available brass quality and the small rifle primer size of the SM compared to the large primer in the XC. However, neither of these now apply, or necessarily benefit you. 6XC brass can be formed from .22-250 Rem and we'll get Lapua .22-250 later this year. Also, Brian Fox (Fox Firearms UK in Stockport) will take Norma brass orders and so should be able to obtain Norma 6XC cases if required - it's pricey though, likely £1 / case and it takes time as the importer will only add small orders onto their next large one which only happens once or twice a year. Either way though that solves the brass quality issue. (Actually, most people use Winchester .22-250 cases and they're more than good enough unless you're going to shoot F-Class at long-range or similar.)
At full-throttle loads, 6XC barrel life is around 2,000 rounds. That is not that much better really than .22-250 or .243 Winchester. There is a lot to be said for the old .243W in the type of shooting you're doing with 55-75gn bullets for foxes. A 243 with a quality barrel can shoot as well as most cartridges if fed good handloads. There is lots of good quality brass to be had off the shelf and at reasonable prices. Likewise you can get match and/or bushing dies etc without any trouble - no special ordering and high prices as with 6SM, no case-forming as with 6XC.
While the SM brass small primer is (possibly) a plus with a match action with a small dia. tightly fitting firing pin - BAT, Barnard, RPA etc - it is a mighty disadvantage with your factory 700VSSF set-up. A large diameter and relatively loosely fitting pin will likely see you get primer cratering / piercing before you reach full pressures and restrict your loads. (Been there, got that T-shirt!) The 6XC (or any other cartridge based on the .22-250 or 308W cases) with its large primer is probably better suited to your action. In the USA, 700 action users can get Gre-Tan to turn down their firing pin and bush the bolt body at a very reasonable price - we've nobody doing this job on a regular basis in the UK, so it would be pricey if you find you need to have it done.
The 6X47 Lapua case and its 6mm wildcat offshoot also use small primers, so you could suffer the same problems there. I have a rebarrelled .308 FN SPR (Winchester 70 WSM action) in 6.5X47L that suffers really badly from this problem, so I have to run around 200 fps down on people using this cartridge in rifles with custom actions otherwise I pierce primers, even using SRM or BR types with their hard cups.
I hope these thoughts help.
Laurie,
York, England
