For those of you who chronograph your loads what is the highest level of standard deviation you feel acceptable?
Acceptable Velocity Standard Deviation?
- Thread starter DamnYuppie
- Start date
Re: Acceptable Velocity Standard Deviation?
That depends on what you intend to do with the load. The farther you shoot the lower your SD needs to be because the greater the vertical dispersion due to velocity variance. If you want to shoot 1K and beyond look for single digits.
That depends on what you intend to do with the load. The farther you shoot the lower your SD needs to be because the greater the vertical dispersion due to velocity variance. If you want to shoot 1K and beyond look for single digits.
Re: Acceptable Velocity Standard Deviation?
That is good to know. I will not make it past 1k. The current load I have worked up is showing a sd of 12. I will do some more testing on it and see if it is consistent over 30+ rounds.
That is good to know. I will not make it past 1k. The current load I have worked up is showing a sd of 12. I will do some more testing on it and see if it is consistent over 30+ rounds.
Re: Acceptable Velocity Standard Deviation?
When I started weighing cases extreme spread went from about 100 fps down to about 40 fps. I use an F1 chrony. I still haven't started annealing yet. Single digits might be a while before I can get to that. Standard Deviation in the low 20's.
When I started weighing cases extreme spread went from about 100 fps down to about 40 fps. I use an F1 chrony. I still haven't started annealing yet. Single digits might be a while before I can get to that. Standard Deviation in the low 20's.
Re: Acceptable Velocity Standard Deviation?
Try to get them around 9 and below. It does take more time but the effort is worth it.
Try to get them around 9 and below. It does take more time but the effort is worth it.
Re: Acceptable Velocity Standard Deviation?
How to evaluate the ES & SD values that will do what you need in hand loaded ammo.
http://www.snipershide.com/forum/ubbthre...082#Post2046082
How to evaluate the ES & SD values that will do what you need in hand loaded ammo.
http://www.snipershide.com/forum/ubbthre...082#Post2046082
Re: Acceptable Velocity Standard Deviation?
You can get your loads down to the single digits. Factors that help
- Consistent internal brass volume (or weight sort them)
- Temp stable powder
- Quality primers
- very tight powder charges (within 0.1gr)
- powder charge that sits right in the middle of a node (requires ladder test or equivalent research)
- weight sorted projectiles
- number of firings consistent per case batch
- cases sized and trimmed to the same length
- minimal case sizing (0.001-0.002 shoulder bump OR neck sizing)
Thats about all I can think of at the moment
You can get your loads down to the single digits. Factors that help
- Consistent internal brass volume (or weight sort them)
- Temp stable powder
- Quality primers
- very tight powder charges (within 0.1gr)
- powder charge that sits right in the middle of a node (requires ladder test or equivalent research)
- weight sorted projectiles
- number of firings consistent per case batch
- cases sized and trimmed to the same length
- minimal case sizing (0.001-0.002 shoulder bump OR neck sizing)
Thats about all I can think of at the moment
