Ruger American Predator Velocity

[puppuccino]

This is my first post here. I recently picked up a Ruger American Predator in .308 for my first bolt gun to get into this precision shooting. I went out to the range to get some dope on it and I have a question about my velocity. I was rushed for time so I only shot 3 rounds through the chronograph;

Shooting Federal GMM Sierra BTHP 175gr

2722 fps, 2653 fps, and 2711 fps with an avg of 2695 fps
Temp: 47°F
Humidity: 39%
BP: 30.11 inHG
Altitude: 1663 ft

Is 2695 fps high for 175gr out of an 18 inch barrel? My boss thinks it's super weird that I was getting readings that high, the chrono was 10 feet away from the muzzle. Just looking for some insight as i'm new to the precision shooting world.

 

[Greg Langelius *]

First three shots through the bore?

Even if it wasn't, making judgements and/or basing lasting opinions on but three rounds really isn't going to tell you much of anything.

Save those ideas for when you have maybe a couple of boxes of ammo (or more) down the bore; I think you'll have a better perspective by then.

Greg

 

[puppuccino]

Thanks for the reply, I guess I’ll have to get back out and see what readings I get after some more rounds down range.

 

[Greg Langelius *]

Reading back over my own post, it comes across a bit surly, and that was not the idea I was attempting to convey.

My comments are based on new barrel initial wear and sample size for statistical purposes.

A new barrel is going to shoot differently from any kind of performance you can count on, especially with the first few rounds. While I don't break in new barrels anymore, per se, I do use the first hundred shots to fireform new brass, and random chrono checks show that something is going on during that first hundred regarding velocity and consistency.

As you can see from your own numbers on the first three shots, the velocities are quite different per shot, and the average is probably drawing a double take or two. I seriously doubt it's going to validly represent the eventual average.

New barrels tend to present a bit more bore friction. More friction equates to more pressure, which equates to more velocity. This may be where the question marks are coming from, but just as easily may not.

And finally, be aware that velocities and spreads/averages are useful, but are neither a true indicator of accuracy, nor an issue to get hung up on. Mainly, I simply use them as a very basic foundation on which to figure trajectories/drops. When working up loads; consider that it's the target that is the true arbiter of accuracy, and not necessarily the chrono,

Your plans look fine. Just shoot the rifle for accuracy and understand that your fired Fed GMM brass is now custom fireformed to your chamber. If you handload, great; and if you don't yet, it may be useful to save it for when you do. I suspect that as the round count accumulates, that FGMM is going to start shooting tighter.

Best fortune with your new rifle.

Greg