Load Development Group Size Vs SD, ES

[Stan Malinky]

New Build 6mm CM 26" Hart # 7@ 7 Twist. I have been reloading for 30 years and I have never used Velocity as a load development tool, just Group size. With the availability of new radar type chronographs such as Garmin's Xero C1 I have decided to use SD and ES as an input to load development. This approach has developed more questions than direction. In my mind I feel a low SD is an indicator Technique Powder Wt., Brass prep, neck tension, seating depth etc. and a tight group is all the above plus shooting skills. I have attached a target showing the SD at each group. Distance 100 Yds, 3 shots at each target.

Any comments will be well received!!!

 

[BRADMOTO]

It's a relationship between barrel harmonics & combustion. You can have the harmonics jiving with a load with high ES/SD, or low ES/SD and bad harmonics. (Groups)

The dream is to have both jive. There's more at play with lower ES/SD though. Like the barrel and components quality.

Shooting 1000yds and more, the great grouping 100yd load with high ES/SD gonna show those results it out there.

Inside 600 not so much. I hunt to 500yds so I don't care about ES/SD, just the precision. I do want both to jive at 1000yds plus.

 

[Stan Malinky]

It's a relationship between barrel harmonics & combustion. You can have the harmonics jiving with a load with high ES/SD, or low ES/SD and bad harmonics. (Groups)

The dream is to have both jive. There's more at play with lower ES/SD though. Like the barrel and components quality.

Shooting 1000yds and more, the great grouping 100yd load with high ES/SD gonna show those results it out there.

Inside 600 not so much. I hunt to 500yds so I don't care about ES/SD, just the precision. I do want both to jive at 1000yds plus.

Now that makes perfect sense, Thanks for the contribution!!

 

[waveslayer]

@BRADMOTO is 100% spot on