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I have a .358 win. Would like to put a .257 Roberts browning factory barrel on it. Will the mag. marked .243, 308, 358 win still be useable? Would a 7mm-08 cartridge and barrel be a better choice since it is based on the 308. I have loaded the mag. with three 7mm-08 cartridges and fed one into the receiver with no problem. Any advice or info. would be appreciated.

HJS
 

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I'm not familiar with the case specs/dims and all for the .257 Roberts, and wondering if you can even use the same bolt assembly etc. with that choice as well? I know it's based on the 7x57 Mauser case, but that's about it, not sure how it matches the .308 family of cartridges. I do own a Browning A-bolt rifle in 7mm-08 and love the caliber (have a .358win BLR too), so I'd probably go that route if your .257 choice required more mods besides the barrel. Actually, on the next BLR I had planned to buy I was going to go with another 7mm-08.
Hopefully somebody smarter than me on that conversion will come along to help you. Good luck to you.
 
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Well from what I can tell the 257 Roberts is a very close match to the 308Win case, other than the rim which is a little narrower by .022. In my opinion the magazine will not be a problem. The bolt carrier will need a little attention but nothing that can't be remedied. On another note what will you be doing with your 358win barrel? I would be interested in it for the right price. Good luck with your conversion.
 

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All kinds. Enamored of their mechanisms! Worked as an engineering
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7mm 08 would be the perfect match, as its pedigree is the .308 Winchester as is the .358. The .257 case is 57 mm long vs the .308 which is almost a 1/4" shorter at 51 mm. Should be turn-key. AC
 
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