Comparing chrono data to results on target

[Wildstreak]

I see a lot people talking about looking for a velocity node and looking at ES/SD as the first step to their development process. Then I guess they tweak loads based on that data.

I would say that I don’t fully understand this but the truth is I have no idea how to interpret this data.

For example, Thursday I shot 2 rifles, a 6.5CM and a 280 ackley. I shot 6 groups of 3 round robin style out of each rifle starting at one charge weight and moving up .2 grains respectively.

For both rifles my best group on paper had the worst ES and SD.

What am I supposed do with that?

 

[Rick Richard]

I see a lot people talking about looking for a velocity node and looking at ES/SD as the first step to their development process. Then I guess they tweak loads based on that data.

I would say that I don’t fully understand this but the truth is I have no idea how to interpret this data.

For example, Thursday I shot 2 rifles, a 6.5CM and a 280 ackley. I shot 6 groups of 3 round robin style starting at one charge weight and moving up .2 grains respectively.

For both rifles my best group on paper had the worst ES and SD.

What am I supposed do with that?

Nothing if you’re not shooting long distance. But, if your shooting way out there then you will see shots scattered about.

 

[Wildstreak]

Nothing if you’re not shooting long distance. But, if you’re shooting way out there then you will see shots scattered about.

500 yards.

Care to expand on that a little?

 

[Rick Richard]

500 yards.

Care to expand on that a little?

For example, ES that has a spread in excess will have impact points high and low which may be outside of an effective kill zone in longer distances…simple physics.

 

[southpa]

Basically you want everything as consistent as possible. Consistent is as close to repeatable as we can get when it comes to your loads. If your bullets are exiting the barrel at the same (or close to the same) velocity every time your drops are consistent amd repeatable. If you have swings in velocity your numbers are not repeatable and you have impacts high/low representing that. As Rick said above, if you're not shooting too long it's not as important but it is exponential the further out you go. Simple physics just as Rick stated.

 

[FireFlyFishing]

Don’t sweat it at 500 yards. Looks at how your groups print on paper at that range instead.

 

[FireFlyFishing]

 

[Wildstreak]

Don’t sweat it at 500 yards. Looks at how your groups print on paper at that range instead.

500 yards is my self imposed limit on animals. The groups in question were shot at 200. Probably should have included that info in the original post.

 

[Mikecr]

For both rifles my best group on paper had the worst ES and SD.

You're seeing a reality that barrel tune and powder tune are separate and different.
Do you want cold bore accuracy or hot precision (grouping)?

 

[Rick Richard]

500 yards is my self imposed limit on animals. The groups in question were shot at 200. Probably should have included that info in the original post.

Curious what were the results in ES, SD and group size.

 

[Eric H]

If your cold bore shot is accurate, you'll only need one. Don't go down that rabbit hole of trying to make your hunting rifle shoot like a precision target rifle.

 

[Rick Richard]

I hear cold bore vs warmed up barrels as something that may be acceptable and normal. For me NOT. If it won’t shoot the same, then it gets worked on including barrel replacement or it goes down the road…don’t have time for aggravation.

 

[Wildstreak]

Curious what were the results in ES, SD and group size.

This is the 6.5 shot at 200. ES was 22 and SD was 12.6

 

[Wildstreak]

Curious what were the results in ES, SD and group size.

This is the 280. I was not happy with any of the groups out of that rifle. SD was 13.25 and ES was 26.5

Interesting though, that particular powder charge had shot pretty well previously, I had a couple half MOA groups at 300 with that powder charge.

The group pictured was shot with virgin brass though it had been sized and processed. Possible that had something to do with it. Don’t know.