Low ES AND SD but still bad groups ?

[Bratcher02]

So I have a savage model 10 in 6.5 CM have a load with 140RDF over 42.5 gr H4350 which this winter done really good for me now summer comes along and things have opened up to about 1 1/2” group at the biggest! Which I know the heat can play a factor so I did a ladder test today and found a couple places that looked to be a node in the rifle in this heat we have now which i will try tomorrow. But while I was out and had the magnetospeed hooked up I shot some of the old load across it and my SD WAS 2.4 with a 5 shot group but still have a 1 1/4” group at 100 yards SMH i shot another rifle and another load while I was out to make sure it wasn’t just me having a bad day but those all shot 3/4” or better ?
So the question is with that low of a SD has anyone found a load not shoot good ? I’m guessing it might be because it’s on the end of a node and the barrel vibration may be off because of it not being in the center of a node maybe ? Just thought my load being that consistent it will still group well? Any thoughts or help would be great thanks Adam

 

[Kadams1563]

What about seating depth?

Also what speed were you running with that charge?

I run 42.2 is 2820 in my 26” barrel.

 

[Bratcher02]

I’m about .030 off lands and average was 2822 FPS
SD OF 2.6 and ES 7

 

[Juggerxxx]

I see that quite often when running through the charge range. Even had five shots that registered an ES and SD of 0 and it was not the best group. Check all your hardware and make sure everything is tight and torqued as it should be. Scope and action screws. Makes sure your parallax is set correct. The target and reticle should not move when you move your head from side to side. Try a different bullet. As mentioned, pick the powder charge node you want and do a seating depth test. Have someone else shoot a five shot group with the rifle.

 

[Bratcher02]

Yeah I done all you stated except have another shooter shot it but have took out other rifles the same day and shot them in front and behind that one all was sub Moa groups I think it’s the load cause I broke the gun down and put back together 2x and re torqued everything starting to play with action screw torque some cause I have moved to a XLR element chassis which they recommend 65inch pounds and the factory savage stock was 40 inch pounds so going drop to 40 inch pounds today and see if that is it

 

[B y r o n]

SD is nothing more than a measure of consistency of the rounds velocity. If that velocity and pressure are not optimum for that barrel then it wouldn't make any difference if the SD was 0, they still would not produce the best groups. Find the load that gives the best groups and then work on assembling the rounds for the lowest SD.

 

[CharlieNC]

Unless you're entering a contest for ES and SD, forget the chrono and use the target to define the node. Barrel harmonics and the associated compensation define the node. After that is done then use the chrono for characterization and improvements to loading technique.

 

[Pvt.Donut]

I'd maybe try some other seating depths. I've heard RDF's like to seat deep. I think I run mine at 0.090" off the lands.

 

[Bratcher02]

Ok thanks for all the info sucks cause this winter it was shooting really good with this load and I know temps play a factor just didn’t think it would open up this bad I’ll go back to the basics and work up another load I guess