Chronograph Help needed

[LIUNA]

Well, I have been reloading about 12 years and decided to buy a Chronograph, what I need to know is when you shoot a group, and your string says duplicate Velocity, how significant is that, and if your target showed a wide bullet placement could that suggest wrong powder of wrong weight of bullet, I can't seem to find any information about chronograph results and what they mean. Now I know this website is full of bright and knowledgeable shooters, so I am relying on some help. Thanking you in advance for your considerations.
Bob

 

[halfmoanut]

The use of a chronograph should be for finding likeable nodes for the barrel on the rifle.It will also tell you how good your reloading technique is, how precision your brass is and a accurate velocity for that barrel. Your extreme spread should be low (10-25) and the sectional density should be lower yet(5-15).I have seen higher numbers on both es & sd and the bullet will still be in the group @ 100-200yds however at 600 those higher numbers for those bullets might be a higher or lower bullet on the target.Horizontal bullets out of the group are most likely due to wind or bench technique of some variation. Most important however remember this nothing trumps accuracy.(nothing).

 

[CoverDog]

halfmoanut.....In your explanation I think you ment to write one thing and wrote another. Been there, done that.

ES on a chronograph printout stands for Extreme Spread. SD in the printout stands for Standard Deviation, not sectional density.

 

[halfmoanut]

Thanks CD, You are correct.

 

[BoydAllen]

A chronograph is a useful tool but just because a load produces uniform velocities doe not mean that it will be accurate. On the other hand, using loading techniques that produce more uniform velocities, can make a good load better. You have a tool that will give you useful information, but the target is the primary tool for working up an accurate load. Close to 30 years back, a benchrest shooter told me that he could learn everything that he needed to know about a load by looking at his targets. Since then, I have acquired a chronograph, and would have to say that while he was mostly right, that there are exceptions. I use mine infrequently, but when I do, the information that it gives me is useful.

 

[CaptainMal]

Sometimes your shots are identical. My chronograph also sends the same, duplicate message at times and I do not think it's a mistake.

Chronograph and accuracy can be related. Again, sometimes they are not. I have had good ES and hideous grouping. Cannot say I've had good grouping with big ES. That chronograph is informative. That's my conclusion.

Saturday I "cleaned" the 600 yard gong match at Manatee. People came to ask what that Dasher shot and the load. A chronograph supplies the answers. It does NOT make a gun shoot.

 

[GermanS1]

Bob, this article by Ken Oehler might be useful to you:
http://riflemansjournal.blogspot.de/2010/02/reloading-velocity-decisions.html

Another interesting piece is this one on Statistics for Rifle Shooters:
http://riflemansjournal.blogspot.com/2010/07/statistics-for-rifle-shooters.html

 

[Steve Blair]

As Boyd said, a chronograph is not necessary for accurate loads. At short range, the target is all that matters. At Mid or Long Range (600-1000 yards), a chronograph is useful but not absolutely necessary. You could use ladder testing to determine whether velocity variation was affecting vertical dispersion. I only have 300 yards available for load development, so a chronograph is a good method for me. If you have 600-1000 available, it is not strictly necessary.