Tikka 243 - pet loads - heavier pills

[SCJ429]

Like another thread I’ve commented on, the problem is your bullet jump.
You need about 15 thou off the lands with 243 or 7mm08.
Heavier bullets get too close with COL around 5 thou.
Try less powder and deeper seating the heavier pills to 15 to 20 thou.

I tried a jump test today and the results were surprising. It was hot and windy so no personal best groups. I tried a 10 thou jump, 40 thou, 70 thou and 100 thou. Best ES was 12 from 10 thou jump and the worst was 22 from 40 thou jump. Best group was .320 from 100 thou jump but conditions were at their best, worst group was .570 from 10 thou jump but mainly horizontal dispersion.

The bullet was a Sierra Match King don't mind a bit of jump, the thing that surprised me is I lost nearly 100 fps when jumping by 100 thou. I would have thought the speed would have gone up.

[Express404]

What's ES and SD..?? young bucks (YB)..??
Last 40 years I thought SD was sectional density and that don't change ...

[animalpest]

What's ES and SD..?? young bucks (YB)..??
Last 40 years I thought SD was sectional density and that don't change ...

ES is extreme spread (i.e. fastest to slowest )
SD can be sectional density, or can be Standard Deviation. When you have a standard deviation close to 0, it indicates that the muzzle velocities tend to be very close to the average, meaning they're very consistent in velocity. A chronograph will work out SD for you.

[SCJ429]

Yes, SD from a statistical point of view is Standard Deviation. The chrono spits out the stats which makes things easier.

[animalpest]

Yes, SD from a statistical point of view is Standard Deviation. The chrono spits out the stats which makes things easier.

Yeah, that's what I said

[SCJ429]

Yes, SD from a statistical point of view is Standard Deviation. The chrono spits out the stats which makes things easier.

Yeah, that's what I said

You sure did.

[animalpest]

SCJ429