Ideal velocity

[dbaird]

I heard somewhere that the ideal velocity for .308 winchester with 168-175 grain bullet was 2550-2600fps.Anybody read or heard about this?

 

[rsmithsr50]

sorry no what bbl length ?
they typically land in there some where because of what works in that size case
but a 175 at 2700 works very well

 

[Rdlningcltchdmpr]

I heard somewhere that the ideal velocity for .308 winchester with 168-175 grain bullet was 2550-2600fps.Anybody read or heard about this?

Ideal for safety, different powder's make different speed's. I have seen 5 different powder's all make virtually the same speed within a few fps but one powder would make tiny groups while the others were only (ok). It's the powder that really creates or breaks accuracy.

 

[Straightshooter1]

I heard somewhere that the ideal velocity for .308 winchester with 168-175 grain bullet was 2550-2600fps.Anybody read or heard about this?

Not not too long ago (1-2 yrs???) an old timer, like me but much more experienced, suggested something around 2670 fps tended to produce good results in a wide range of .308's. And interestingly to me, when I look at my data for the 168 and 175's I've fired, that was pretty close to what I see.

In using QuickLoad app for help with having an idea of what I'm loading and how it relates to my results, I keep and eye the the PSI that works, which is something at 58,000-59,000 no matter what length barrel I put on the receiver. So, for example, in using 43.6 gr of Varget with 175 SMK's in my 26" barrel my chrono gives me an average of around 2,665 and QL app calculates a pressure at 59,000 psi. Using 40.5 gr of AR-Comp my chrono gives me an average of around 2,688 fps out of the same barrel where QL calculates a pressure at 58,400 psi. For my 20" barrel I'd get around 2,530 fps, with the same pressure. And for whichever barrel, these loads are the one's that gave me excellent results.

 

[Lefty Trigger]

Depends on your shooting style. Accuracy is not always the fastest velocity but the slowest might not go the distance with the needed results. I have found that I can get some serious "short range" accuracy with some really slow loads. I have one load for my 308 that is dead on 2600 fps with an ES of 4 using Norma 202 powder with 168gr Sierra's.

 

[Ned Ludd]

I heard somewhere that the ideal velocity for .308 winchester with 168-175 grain bullet was 2550-2600fps.Anybody read or heard about this?

Optimal velocity totally depends on the rifle setup and load (i.e. barrel length, freebore, powder, primer, case volume, etc.). With a 30" barrel as is commonly used in F-Class, I would expect ~2800 to 2900 fps from a tuned load with 175s or 168s. From that perspective, the velocities you listed would be considered extremely slow/mild. From a standard 24" test barrel, even factory 175 loads are typically in the 2600 to 2650 fps range, 168 loads a bit faster. The only "ideal" factors that really exist regarding velocity are:

1) you have to be able to achieve a given velocity at safe operating pressure
2) an "ideal" velocity associated with optimal precision will have a specific relationship to the barrel harmonic cycle

Otherwise, there is no such thing as an "ideal" velocity for any given caliber or bullet weight. The ideal velocity will totally depend on the specific setup. I suspect such terms as "ideal" velocity get thrown out there because there are certain loads that have been well known for their accuracy/precision over the years, and have been used by many reloaders as their "go to" loads. Such loads typically fall within a fairly narrow velocity range out of similar rifles, and might easily give rise to the notion that some ideal velocity exists for a given caliber.

 

[T-shooter]

It will vary on barrel length but with my 22" .308, the 168g bullets (either Sierra or Hornady) fly the best at about 2,570 fps.

 

[rammac]

I heard somewhere that the ideal velocity for .308 winchester with 168-175 grain bullet was 2550-2600fps.Anybody read or heard about this?

This probably came from a M14/M1A shooter. The military will typically specify that their 7.62x51mm (.308 Win) ammo run around 2550 fps for their 22 inch barreled rifles.

 

[rsmithsr50]

specifically
m852 is 2550 fps this is the 168 smk 7.62x51 match round.
mk316mod 0 is 2580 this is the otm 175 sniper round.
these velocities are at 78 ft/26yards, so muzzle velocities are higher.


[959"]This probably came from a M14/M1A shooter. The military will typically specify that their 7.62x51mm (.308 Win) ammo run around 2550 fps for their 22 inch barreled rifles.[/QUOTE]