Help me pick a load node.... ladder test inside

[Tripplet918]

123

[baih777]

Did you do three shot ladder test ?
Need to post the pics of the three shot group.

[smoothy8500]

Are you looking for the mythical "flat spot" with increasing charge weights?

[Kerplow]

https://www.chuckhawks.com/use_chronograph.html

[Whiterabbit]

Can’t do one shot, you need averaging. Many of those loads has a huge ES. So its easy to mistake the flat spot.

If I were a betting man, I would bet your nodes are 2 grains apart and 0.5 grains wide. If that were true, you can pick the upper node to eke out more velocity. But do you pick the bottom of the node or top? Which has better ES? Where DOES that upper node start and end? I have no idea from the plot. I would tho with three shot groups.

Up to you of course. You can take a shot with what you got and hope for the best.

[Whiterabbit]

Well, good luck to you then!

Though, one might conclude if that were a true statement, and the Satterlee method was valid here, you wouldn't be asking us to help you pick a load node because it would be obvious.

Right?

[Whiterabbit]

I know you get my point already (and disagree which is OK!) but this is for others:

Here's a (real) example of the same kind of test done with 3 data points each to pull an average. Imagine taking a "random" data point for each charge weight and plotting the resulting graph. What is the likelihood of coming to a VERY different conclusion regarding where the flat spots are compared to the "average" line? To say nothing about getting a sense of possible ES and SD of a particular charge weight.

edit: removed BB Code image because it was too big

[LynnJr]

When i do a ladder test i only look for vertical between the shots and not the velocity of the shots.

[smoothy8500]

ES averages 8-12. On exceptional days, Ive had ES as low as 5.....I will validate the final load for vertical dispersion at 600 yards over 10 rounds.

Just casually ran some numbers through Hornady's ballistic calculator: At 600yds an ES of 30fps creates 1-1/2 inches vertical dispersion.

That's only 1/4MOA. Not a lot in the big scheme of things

At 300yds it's almost negligible. Seems like testing for vertical dispersion would be more useful. Unless you're looking for that "flat spot" where plus/minus .3gr doesn't affect velocity. At that point, you can just use your Lyman thrower on a progressive and not worry about anything.

Of course, those numbers got a lot bigger at 800yds and especially past 1K where ES does matter.

[Whiterabbit]

40 and 43, but mostly 40. ES was king because the powder is measured precisely. Thus, I did not need to select a flat spot, but did need to make sure I was not inherently in a zone of high ES. The rest was tuned with bullet choice, primer choice, and OAL.

[Sir Toast]

That graph doesn't make sense to me.

however, I always take accuracy over velocity.

I have no idea the size of the groups compared to velocity by that graph. But then again, I'm Toast. good night.

[Whiterabbit]

I for one do get it. I just don’t agree with that school of thought. The concept does not agree with my experimental data. I guess his mileage varied.

I’d agree with the method if every load in the work up had a known ES of zero.

[smoothy8500]

The objective here is to find the flattest velocity change between charge weights to find the most consistent velocity (accurate) even with some charge weight inconsistency,

I've used both Satterlee and Newberyy's OCW methods. I found the OCW more effective for me. As you noted, the PRS shooters are typically wearing out a barrel after 2,500 rounds. Trying to use seating depth to tune the accuracy is like following a moving goalpost as the throat wears.

Despite some variability in velocity, the POI is consistent.

[SmokeTheClay]

The vertical dispersion is pretty much your velocity differences. Faster impacts higher and vise versa.

The thing about impact points, it includes the human element. If you agree that vertical dispersion is the direct result of velocity differences, then an accurate chronograph reading would be pretty much the same.

If you dont, thats cool too. Ive done it a few different ways, they all work.

At the end of the day, we do whats works best for each us. If you have the components, barrel life, reload and range time, then have at it.

[divingin]

Can you look at the chart below and let me know what you think would be the best node. Trying to get a consensus. 43.1 grain is where it seems to flatten out, my other option is 42.8. If 41.5 didnt shoot up like that, that may

I have no idea how you are inferring your thoughts from that graph. The only flat spot I see is 41.5 to 42, and that's arguable. Everywhere else is a rising slope, which infers no flat spot.

The underlying premise to the method is that barrel harmonics differ from charge weight to charge weight. What one is looking for is the most accurate grouping from a particular charge weight.

Vibration through a piece of steel is not going to change. What does change is the time the bullet spends in the barrel. Tuning the charge is trying to get the bullet to leave the barrel as the "swing" of the muzzle is at its slowest (generally one of the extremes, I think.)

I sort of have a feeling (can't prove this) that a lot of the depth tuning is actually tuning the load by changing the pressure the shot runs at. I know people will disagree.

I use a ladder test, but look at the groups rather than looking for velocity flat spots. It's easier, and more relatable to real world results. That's just me, though.