.308 match ammo

[Sodbuster]

Can anyone give their insights into the differences between Federal 168-grain and 175-grain match ammo? Do the extra 7 grains of the 175-grain impart that much difference as far as drift and trajectory are concerned? Might I throw in Lake City 173-grain to really confuse the issue? John Plaster gives a lot of info concerning the Federal 168-grain, but there seems to be little published on the 175-grain. Thanks for any input.

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Hoka-hey

 

[fed168]

The 175 gr. is pretty new to the scene. It was my understanding that this bullet bucks the wind better and produces a better trajectory at 600 yards plus, if I remember correctly. No experience with it yet, pretty happy with 168s.

 

[Cheapo]

My pop was one of the first to use the Sierra 168, when it was called the "International Match" bullet. In the .308/7.62mm, it just cannot be safely pushed fast enough to stay supersonic all the way to 1,000 yards. (IIRC, they go subsonic at about 925-950 yards.)

The USGI will stay supersonic to 1,000. The open-base, closed tip design just cannot be made to shoot as accurately as HPBTs, in part because the bullet heel has the greatest effect on accuracy. The extra 5 grains does make a difference. Takes only 75-100 yards...

The Sierra 175, if I understand it correctly, not only has the extra weight, but also incorporates a slightly slicker "VLD" design, like the really neat 155-gr "Palma." That one can be launched fast enough from a .308, for its low-drag design keeps it above transonic velocities all the way past 1,000.

All this is important because wind drift and group size increase dramatically in the turbulent world of transsonic velocities. Took the handgun silhouette shooters a few years to figure that one out--old news to HP shooters.

BTW, the USGI 173 can produce group sizes of about 3/4 MOA from the right barrel/chamber combination.