Interesting Chronograph Data Interpretation Exercise

[Rio Precision Gunworks]

Here's some chronograph data from a 6gt with common charge weights of Varget. 5 shot strings.

If you performed this test, what would your interpretation be? Would it be that 33.6 to 33.8 is a good area? Or would you interpret it in a different way?

(apparently if you aren't in dark mode, some of the graphs won't show. added two screenshots in the pics for those that need them)

 

[308pirate]

Load 33.6 gr and quit fucking with it.

 

[giumau1]

What @308pirate said. Load 10 next time

 

[Hula Popper]

Big increase in the slope (deltas) between 33.6 and 33.8 (gamma3 = 165 fps/grain)- indicates powder charge (pc) area of possible instability or statistics catching up with you. Other gammas more consistent, especially between 33.8 and 34.0. Would check 5 or 10 rounds at 33.5, 33.7, and 33.9 and see if those results are consistent with the first go around. Grouping is another matter.

Or do as @308pirate "suggested".

 

[Doom]

Big increase in the slope (deltas) between 33.6 and 33.8 (gamma3 = 165 fps/grain)- indicates powder charge (pc) area of possible instability or statistics catching up with you. Other gammas more consistent, especially between 33.8 and 34.0. Would check 5 or 10 rounds at 33.5, 33.7, and 33.9 and see if those results are consistent with the first go around. Grouping is another matter.

Or do as @308pirate "suggested".

View attachment 8339066

CHECK YOUR NUMBERS.

 

[Doom]

Here's some chronograph data from a 6gt with common charge weights of Varget. 5 shot strings.

If you performed this test, what would your interpretation be? Would it be that 33.6 to 33.8 is a good area? Or would you interpret it in a different way?

(apparently if you aren't in dark mode, some of the graphs won't show. added two screenshots in the pics for those that need them)

View attachment 8338984 View attachment 8338985View attachment 8338986View attachment 8338987View attachment 8338988

I wonder why you are looking at 5 shots on a chronograph and wonder why you are not looking at the target.

 

[straightshooter1]

Here's some chronograph data from a 6gt with common charge weights of Varget. 5 shot strings.

If you performed this test, what would your interpretation be? Would it be that 33.6 to 33.8 is a good area? Or would you interpret it in a different way?

(apparently if you aren't in dark mode, some of the graphs won't show. added two screenshots in the pics for those that need them)

View attachment 8338984 View attachment 8338985View attachment 8338986View attachment 8338987View attachment 8338988

Chronograph numbers are good at telling you how well you're loading your cartridges, but doesn't really tell you anything as to what kind of precision you can expect on target. The shapes and relative position to POA's on targets is what you need to interpret.

 

[308pirate]

Chronograph numbers a good at telling you how well you're loading your cartridges, but doesn't really tell you anything as to what kind of precision you can expect on target. The shapes and relative position to POA's on targets is what you need to interpret.

How about interpret ALL available data without disregarding one or the other?

I'd start screwing around with seating depth changes to fine tune accuracy once I found a stable range of powder charges (which I did above)

 

[Hula Popper]

CHECK YOUR NUMBERS.

Thanks. Oh boy, GIGO - revised my "spreadsheet". Had to pull it out of the "Recycle Bin". That's what happens when I multi-task. Still a big increase in the slope between 33.6 and 33.8, and that's what caught my eye when first looking at the data. The slope between 33.8 and 34.0 now seems more consistent with expectations. Agree about seeing grouping with chrono data.

Don't know much about 6 GT - What would the target MV be?

 

[mrcheesemoose]

TBH the confidence intervals of all the strings overlap too much, so it’s impossible to really tell the difference between the strings. You need more data