Free bore amount for 308 Win using 168g Sierra MK

[AckleymanII]

What is the best freebore for the 168g MK, I need to order a reamer for this bullet in the 308 Win.

Will be shot in a Rem 700, and I suspect that it will exceed the mag length.

Thanks in advance

 

[LA50SHOOTER]

What is the best freebore for the 168g MK, I need to order a reamer for this bullet in the 308 Win.

Will be shot in a Rem 700, and I suspect that it will exceed the mag length.

Thanks in advance

A 0.155 Free bore will let you run ammo in the 2.840 COAL range and you'll be able to keep the bearing surface above the neck / shoulder junction. - Will work fine for the 175 SMK & 185 Berger's as well.

 

[Ned Ludd]

A chamber with 0.085" freebore is commonly used for .308 Win commercial ammunition with 168s/175s. I have had a couple of .308 Win F-TR that had relatively short chambers cut with 0.085" fb. They shoot the Berger 168 Hybrids exceptionally well, although they just seat a little for mag length (feeding). Given the similarities in their BTO measurements (the 168 SMKs BTO is ~.030" longer than the 168 Hybrid, but the 168 SMK is ~.070" shorter in OAL than the 168 Hybrid), I'd imagine it would work very well for the 168 SMKs. Having said that, there are certainly better choices in bullets than the 168 SMK. The 175 SMK, and/or 168/175 Tipped MKs would be much better choices, for example.

The 0.085" freebore generally works well for bullets up to around 180 gr, but it is a little on the short side for something like the 185 Juggernaut, if you might ever have any interest in shooting those, perhaps down the road. You could increase that fb to somewhere in the 0.100" to 0.120" range, which would work a little better for something like the Juggernaut, while not forcing the 168s to be seated anywhere close to excessively far out the neck. In any event, if you speak with a representative from JGS or Manson and tell them what you want, I guarantee they will have all the information you could ever want or need to make an appropriate reamer selection for use with that bullet.