Ladder test interpretation

[TheJason]

Do you have other powders on hand? H1000?IMR7828? I’d start there if you do.

When you look at Nosler’s load data for this combo, Magnum isn’t even listed.

Both of the powders you mentioned are.

 

[Redmt]

Velocity, bullet weight, rifle twist and dumb luck at picking the right combination have a lot to do with accuracy.
Correct me if I'm wrong but I thought ladder tests were for determining max powder loads. Keep adding powder until the velocity doesn't change or you get pressure signs, whatever comes first.

 

[golfer]

When you look at Nosler’s load data for this combo, Magnum isn’t even listed.

Both of the powders you mentioned are.

View attachment 359668

I’ve referenced that, but just because Nosler doesn’t list it doesn’t mean it is not an option.

 

[TheJason]

I’ve referenced that, but just because Nosler doesn’t list it doesn’t mean it is not an option.

I realize that, but in my experience Nosler has some of the best data out there for choosing a good powder for your bullet. You can obviously use powder they don’t list, but your results will likely mirror what you are currently experiencing.

 

[golfer]

Do you have other powders on hand? H1000?IMR7828? I’d start there if you do.

I do, H1000 was third on the list of powders. I’m gonna try to stay away from 7828 if possible. Before this barrel got replaced I had excellent results with rl26. Was seeing 3460 with 68.3gr. So next step will be to play around with 26.

 

[yakimanoob]

Correct me if I'm wrong but I thought ladder tests were for determining max powder loads. Keep adding powder until the velocity doesn't change or you get pressure signs, whatever comes first.

Normally the ladder method is supposed to help determine accuracy by identifying "nodes" where the velocity flattens across a range of charges before continuing upwards. The idea goes that you've found a spot where the muzzle velocity (and thus the "dwell time", which purportedly controls where in the harmonic oscillation the bullet exits and thus affects accuracy) is more consistent.

Trouble is, that house is built on sand. As many tests have shown, velocity "nodes" are nothing more than statistical anomalies that disappear as more shots are fired / tests are repeated. In technical terms, the relationship between charge weight and muzzle velocity is linear and homoskedastic (at least within published ranges of charge; variance does seem to increase as you push the limits of charge weight and approach pressure signs). On top of this, there is a lot of argument among professional ballisticians about the validity of the theory that accuracy is a function of where in the harmonic oscillation pattern the bullet exits. If that theory falls, so does the foundation of the "ladder test", at least as it relates to accuracy.

All that said, if you're doing a ladder test just to find where pressure signs start, then none of what I just said matters and I rescind my "hot garbage" comment. Sneaking up in charge weight is a perfectly legitimate way of finding the pressure boundaries for your system. It's just not going to tell you much at all about accuracy.

 

[Mtnhunter1]

Normally the ladder method is supposed to help determine accuracy by identifying "nodes" where the velocity flattens across a range of charges before continuing upwards. The idea goes that you've found a spot where the muzzle velocity (and thus the "dwell time", which purportedly controls where in the harmonic oscillation the bullet exits and thus affects accuracy) is more consistent.

Trouble is, that house is built on sand. As many tests have shown, velocity "nodes" are nothing more than statistical anomalies that disappear as more shots are fired / tests are repeated. In technical terms, the relationship between charge weight and muzzle velocity is linear and homoskedastic (at least within published ranges of charge; variance does seem to increase as you push the limits of charge weight and approach pressure signs). On top of this, there is a lot of argument among professional ballisticians about the validity of the theory that accuracy is a function of where in the harmonic oscillation pattern the bullet exits. If that theory falls, so does the foundation of the "ladder test", at least as it relates to accuracy.

All that said, if you're doing a ladder test just to find where pressure signs start, then none of what I just said matters and I rescind my "hot garbage" comment. Sneaking up in charge weight is a perfectly legitimate way of finding the pressure boundaries for your system. It's just not going to tell you much at all about accuracy.

Very well stated, I couldn't agree more. But I am just a hobbyist re-loader that hunts and not a competition shooter.

 

[WapitiBob]

You can't force feed it something it doesn't like. With the right bullet and powder combo you should be done in 30 shots.