I agree with Phil on this. Just because a barrel is marked as a 12 twist doesn't mean that it really is. Clearly, if you order a new barrel you may be smart to get a 10 or 11 twist to be on the safe side.I think the deal is, are the barrels REALLY 12 twist?????????
Just because they tell you it`s a 12 twist, doesn't guarantee it.....
Personally I don`t shoot anything but 32`s in a 12 twist, but I bought 11 twist barrels for all my 39 gr. stuff.....
Doesn't mean it won`t work, just that I don`t happen to do it that way......
You need to try it for yourself, don`t let others tell you that it won`t... it isn`t their rifle, it might work.......It might not.
Good luck with your project.
Phil.