• This Forum is for adults 18 years of age or over. By continuing to use this Forum you are confirming that you are 18 or older. No content shall be viewed by any person under 18 in California.

How dies the ES/SD relate to group size?

Linko

Silver $$ Contributor
I have been working up a load for my 6BR. I am loading 105 Hybrids with Varget Lapua brass and CCi 450's. (Savage Target 30" barrel)

Consistantly I get better ES/SD with 29.7 gr but better ES/SD with 29.6

here is my latest at 100yd

How do these ES/SD numbers relate and is one more important than the other?
 

Attachments

Linko said:
I have been working up a load for my 6BR. I am loading 105 Hybrids with Varget Lapua brass and CCi 450's. (Savage Target 30" barrel)

Consistantly I get better ES/SD with 29.7 gr but better ES/SD with 29.6

here is my latest at 100yd

How do these ES/SD numbers relate and is one more important than the other?
Click to expand...
I'm not quite sure what you're saying. Is there a typo in your post? Do you mean "group size" rather than "ES/SD"?
 
105 hybrid.JPG

The ES and SD are lower with 29.6 and 29.8 but the group is better with 29.7

(The velocity measurements were made with the magnetospeed attached to the barrel, the groups are without it attached)

I would have thought the group for 29.6 or 29.8 would be better
 
Last edited:
First things first....I see that you are testing groups WITHOUT the Magnitospeed. Good for you. I was just going to tell you to trash the thing for group testing, but...I see you already did.

Next.....you will not see any difference on a 100 yard target as far as ES. You need to move way out there...at least 600 yards. And, you didn't say what this will be for....if it is for 1000 yard BR/Fclass, then test at 1000 as much as possible.

Also, guns are funny things, and they don't read the same instruction manuals as we do. The dasher tube I used to win the nationals in 2011 shot HORRABLE ES (40FPS +) during testing, but printed itty, bitty groups on my 1000 yard range. I know it isn't supposed to happen that way, but...........

Good luck, and keep us posted,
Tod
 
I'm shooting the 105 hybrids, Varget, Lapua and 450's same as you although not in competition. My 28 in bbl seems to prefer 30.3 grains of Varget (my lot, not yours), ES and SD in the single digits. Groups at 1000 yds are very tight. A 4 inch target is a bit of a challenge, especially in wind, but that bullet shoots very well. Keep working up, especially at longer distances. Maybe time to move to 200 yds in your load development.

Magnetospeed will alter POI, and if it is moving as firing progresses, groups may tighten and then loosen as the mass hanging off the end of the barrel works like a barrel tuner. Been there, done that. So I shoot two separate groups as you do. One for group, one for speed info.

The basis of good, reliable load development lies in record keeping. You're on the right track.
 
Check the 29.8 group sizes with and with out the magneto speed.
The "with" is better than the with out. Work with the seating depth, I think you will have a real winner.
LitLBoy
 
LitLBoy said:
Check the 29.8 group sizes with and with out the magneto speed.
The "with" is better than the with out. Work with the seating depth, I think you will have a real winner.
LitLBoy
Click to expand...

why do you say the "with" is better than the with out"
 
get a bench mount to put the "speed on for testing.
data from one 5 shot group does not automatically apply to the next 5 shots.
it is tuff to put any serious trust in 5 shot es/sd data, that small of a data set,
the target says it all.
get a real chrono.. labradar/ohler
shoot longer
only one 29.7 is small work from there
 
To my eye the on group 29.8 is smaller and more uniform, thinking the magnetospeed is working like a tuner. Thinking working with seating depth at 29.7 or 29.8 will tune the load.
LitLBoy
 
at the king of two mile shoot in 2017, david tubbs
shot with a magnospeed..BUT
it was mounted on a rod that parralleled the bbl and stuck in his "stock".
 
Linko said:
I have been working up a load for my 6BR. I am loading 105 Hybrids with Varget Lapua brass and CCi 450's. (Savage Target 30" barrel)

Consistantly I get better ES/SD with 29.7 gr but better ES/SD with 29.6

here is my latest at 100yd

How do these ES/SD numbers relate and is one more important than the other?
Click to expand...
When a tenth of a grain makes a difference, you have not found the right node for that load or that rifle. Even at a grand a 2 tenths of a grain load difference will not amount to much if you have the right node. Especially in a case that hold more than 40 grains of powder. Extreme spread is most important of the two numbers, standard deviation is a BS number, IMHO. Standard deviation depends on how many rounds you shoot and how many variables enter the picture. A simple thing like shooting cadence can inhibit your extreme spread. So check your loads at the distance you shoot and shoot at a cadence the conditions will afford. And yes this will exhibit itself more at 300 yards and beyond!! Work on that node, vary the seating depth, powder, and bullet tension. Yes it's a lot of work!
 
what if he is at the top or bottom of a node...then .1 will take him out or over.

LCazador said:
When a tenth of a grain makes a difference, you have not found the right node for that load or that rifle. Even at a grand a 2 tenths of a grain load difference will not amount to much if you have the right node. Especially in a case that hold more than 40 grains of powder. Extreme spread is most important of the two numbers, standard deviation is a BS number, IMHO. Standard deviation depends on how many rounds you shoot and how many variables enter the picture. A simple thing like shooting cadence can inhibit your extreme spread. So check your loads at the distance you shoot and shoot at a cadence the conditions will afford. And yes this will exhibit itself more at 300 yards and beyond!! Work on that node, vary the seating depth, powder, and bullet tension. Yes it's a lot of work!
Click to expand...
 
LCazador said:
.......... snip............. standard deviation is a BS number, IMHO. ......... snip..........
Click to expand...

I'm with you. In fact most numbers are BS. Take Pi, for example. What's with all those digits after the decimal point? Why not just round Pi off to three? Three is a good reliable number and everybody knows it. Mom always told me to not be irrational, and I'm sticking to her advice.

And don't even get me started on Avogadro's number. That danged thing is at least ten to the twenty-three times bigger than it has to be.

Nobody understands standard deviation anyway......... just ask any statistician.
 
You must log in or register to reply here.

Upgrades & Donations

This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.


Click Upgrade Membership Button ABOVE to get Gold or Silver Status.

You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.


To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.

Classified Ads

Forum statistics

Threads
165,810
Messages
2,203,697
Members
79,130
Latest member
Jsawyer09

Share This Page

Back
Top