The smallest sd and es I’ve chrono’d

[V00D00]

And it didn’t group.

 

[43.6N]

Wow.

How many shots? And what cartridge/bullet/powder?

 

[V00D00]

Wow.

How many shots? And what cartridge/bullet/powder?

3 shot group. Looked like a node when I shot a ladder. 7prc 175gn ablr retumbo cci250 adg seated 0.050

68.0gn retumbo. First time I shot the 3 shot group
0.752” 2740fps avg sd 12.6 es 28.5
Felt like I pulled a shot so reloaded it.

Shot it again today.
1.680” 2712fps avg sd 1.8 es 4.3

 

[Andouille]

I've chrono'ed some seemingly impossible SD and ED numbers (very low, very high) and odd velocities (ascending, descending, etc), and while it's tough to wrap my head around how they happened, the answer is usually that there were " too few shots" to show a statistically valid distribution.

Three shots wont tell you much other than you have high ES, or potential for low SD. But if the group is poor, then there's no point in shooting more to prove an SD. I have a rifle that has a load SDs in the teens over 50+ shots but just wont group under 2". Probably time to switch bullets...

 

[Castle Rock]

This one did well on target too
6.5 cm, 140 Bergers H4350

 

[TradLife406]

Of course your sd/es will be low with only three shots.

It is funny back when I had the gram I'd post my 10-20 shot sd's in the teens. Guys would be like dang man that's horrible. Well not really since I was actually using a more valid sample size.

 

[wapitibob]

Lost me at chrono.

 

[RME]

I'd post my 10-20 shot sd's in the teens. Guys would be like dang man that's horrible. Well not really since I was actually using a more valid sample size.

I see that type of thing happening more and more as larger samples are becoming more common. It will take a while for all this to work itself out.

 

[hoooogan]

This was by far my best recording. Same charge but different jumps. Forgot to turn it on both times, so I missed 3 shots out of the 20. But combined 11.2 spread with high 3 SD over 17 shots.

 

[Mtslackcountry]

I have a rifle that shoots 1/4 minute 1 shot groups

 

[V00D00]

If I’m 3 shots in and the group is already +.75” I don’t keep shooting. I’ll move on the the next. I’m not trying to waste time or componets. But even three shots that sd and es is respectable.

 

[Harvey_NW]

3 shot group. Looked like a node when I shot a ladder.

Username checks out.

 

[solarshooter]

3 shot group

There's your problem.

Looked like a node when I shot a ladder

No wait, THERE'S your problem.

If I’m 3 shots in and the group is already +.75” I don’t keep shooting. I’ll move on the the next. I’m not trying to waste time or componets. But even three shots that sd and es is respectable.

What if the next 7 fall inside those first 3?

What if the first 3 are in 0.5" and the next 7 go to 1.5"?

How will you know what the true group size is in either situation?