Re: 308win. ???
If you want to shoot bullets in the 175gr range, I would get the 1:11.25. Barrel length will be more of a preference. I have seen people easily ring steel at over 1,000 yards with an 18" barrel. I have 308's in 26", 24", and 20". I take the 20" hunting a lot because it is so short and easy to handle. There doesn't seem to be any difference in accuracy between the different length barrels. A lot of this is going to depend on what you really want to do with the rifle. I think a 22" or 24" would be a good all around barrel length.
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