Need a little help interpretting my data.

[TheDeicide]

So this is my 28 Nosler with 155g CE MTH bullets in Peterson Brass with H1000 and Federal GM215 Primers. The spreads from 80.9 to 81.3 are unbelievable. The thing that has me puzzled being new to this, is the change between strings. I fired string 1 from low to high and then string 2 from high to low. I plan to load at 81.1 and play with depth or at least I hope to depending on what I can learn about that velocity jump. Also prior to this session I had fired 6 rounds after cleaning, so a semi dirty bore.

Charge​	Str1 Velocity​	Str2 Velocity​
80.9​	3365​	3397​
81.3​	3364​	3397​
81.7​	3370​	3403​
82.1​	3372​	3435​
82.5​	3407​	3436​

 

[Mikecr]

What was the brass shot count for each string?
What sizing was there?

 

[TheDeicide]

What was the brass shot count for each string?
What sizing was there?

new brass, never fired, and only deburred and chamfered.

 

[DUSTY NOGGIN]

barrel temp

 

[catamountsierra]

barrel temp

That would be my guess, especially with the change in firing order. 80.9 and 81.3 were the colder barrel shots in string 1 and the hotter barrel shots in string 2. They also show a bigger difference from one string to the other than the higher charges.

 

[Tiny Tim]

This!^^^^^^^

 

[TheDeicide]

So I assume I'm good to target that node since the ES is so good?

 

[Tiny Tim]

I'd try it. How is your sd? The middle load(s) are the most consistent in firing order. I mean similar barrel temps in firing order, so are less affected by it. If accuracy is good, try stretching it out some.

 

[TheDeicide]

17.9 and 20.1 on the first string and second respectively.
For the heck of it I cleaned up my once fired brass and neck sized it .003" tension today. I loaded 5 rounds with 81.1gr and a site round that was brass used during setup of the die. If I eliminate the flyer I got a group around .58" center to center, ES of 13, StDev of 5.8, and avg velocity of 3421.5 fps. Only shooting 100 yards. I have a range next to the property.

 

[DUSTY NOGGIN]

i would do 1@ 80.7,80.8, 80.9, 81.0, 81.1 ,81.2, 81.3, 81.4, 81.5, 81.6, 81.7 with the same , now chamber formed cases to find the very center of that stable spot

 

[Mikecr]

new brass, never fired, and only deburred and chamfered.

So your brass was not stabilized by this testing. The information means little at that point.