Ladder test and hornady OAL gauge

[Hoons]

Should I do the ladder test first, use the best load and further dial it in using the hornady overall case length gauge or is it typically done the other way around?

 

[ToolAA]

Should I do the ladder test first, use the best load and further dial it in using the hornady overall case length gauge or is it typically done the other way around?

A lot of the approach depends on the specific caliber and if it’s intended for a bolt action or semi-auto. In general for bolt action, I measure my chamber and start out .020 behind the lands for my current bolt action loads. For semi-auto I go with the SAMI spec for COAL. Then I work up charge weight using Dan Newberry’s OCW method.


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[Hoons]

I'm loading 223 for semi. I'll have to look up that method, thanks.

 

[Speed3]

I've seen people do it a number of ways. For bolt guns id start .020 off lands, .04 off for semi. I used to use a ladder test increments of 1% of the charge weight (20gr, 20.2gr, etc).

The last 2 barrels I've loaded 20 to 25 rounds .020 off lands and gone up in .1gr increments in powder and run over a Labradar for speed. I plot the speeds in excel and its easy to see the powder nodes. For larger cartridges maybe .3gr makes more sense.


Next step for me I to do a ladder on seating depth. I go .003" change in seating depths. Im looking for 3 variants that shoot good(same vertical and horizontal) and settle close to that.

Example, load at 2.000, 2.003, 2.006, 2.009. If the last 3 were the best group, id load to 2.008 to allow for throat erosion and not be out of the node.

 

[ToolAA]

I'm loading 223 for semi. I'll have to look up that method, thanks.

Are you loading special purpose rounds? i.e. Match Shooting, Home Defense, or General Plinking.
Would you be using these rounds ONLY in the one rifle?

 

[Hoons]

Plinking and 3gun rounds in two different rifles

 

[Hoons]

What is a powder node?

 

[ToolAA]

What is a powder node?

Refering to OCW? Basically the theory is that as the rifle is fired the barrel will vibrate or rather oscillate. The goal is to have the right charge to have the bullet exit the barrel when this oscillation is closest to the barrel axis (not at the extreme limit).

So a node is the point where the bullet leaves the barrel exactly at this point of least deflection. Since the barrel is oscillating several times in the span it takes the projectile to start moving until it exit’s the barrel you could have situations where less powder may cause the bullet to exit say on the 4th barrel oscillation cycle but more powder and a faster velocity might have the bullet leave the barrel on the 3 oscillation cycle. These timed occurrences are nodes.


I also wanted to go back to your initial question about bullet seating depth. Since one of your use cases is 3gun and you will load for two firearms, I would just stick with the SAMI seating depth spec. At those close ranges I don’t think you would see the benefits precision seating.


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[trickg]

I've seen people do it a number of ways. For bolt guns id start .020 off lands, .04 off for semi. I used to use a ladder test increments of 1% of the charge weight (20gr, 20.2gr, etc).

The last 2 barrels I've loaded 20 to 25 rounds .020 off lands and gone up in .1gr increments in powder and run over a Labradar for speed. I plot the speeds in excel and its easy to see the powder nodes. For larger cartridges maybe .3gr makes more sense.


Next step for me I to do a ladder on seating depth. I go .003" change in seating depths. Im looking for 3 variants that shoot good(same vertical and horizontal) and settle close to that.

Example, load at 2.000, 2.003, 2.006, 2.009. If the last 3 were the best group, id load to 2.008 to allow for throat erosion and not be out of the node.

How do you really "know" where the lands are?

I like Erik Cortina's method for finding the accuracy nodes when it comes to seating depth.

First he gets his two extremes - jump, and jam. Once he knows jam, he backs off and tests - he doesn't actually care where the lands are - he only cares if his load is accurate, and what his seating depth is at that point.

He explains it pretty well here:



Keep in mind, I'm pretty new to rifle reloading, but I like how Erik Cortina explains things. It makes sense from a common sense perspective, and he's one of the top shooters in the country, so it's pretty safe to say that he knows what he's talking about.

 

[Speed3]

How do you really "know" where the lands are?

Hornady sells things to measure lands. It only needs to be measured on a new barrel from the start for initial load development. You need to know where lands are to know where to either jam(dont recommend) or jump(baseline plus .020")

I agree with erics approach and that's largely what I've followed for the last 2 barrels. It works well for me and doesn't waste a ton of rounds in the process.

 

[trickg]

I agree with erics approach and that's largely what I've followed for the last 2 barrels. It works well for me and doesn't waste a ton of rounds in the process.

I like Erik's approach for a couple of reasons. For one, it requires no other tools than a good set of calipers and some die wax, and like he states, you don't really need to know or really even care where the lands are because how you seat your bullet depends on the bullet you decide to use since each bullet has its own distinct ogive. As long as you find the accuracy node for your barrel/rifle, that's all that really matters.

 

[Hoons]

Refering to OCW? Basically the theory is that as the rifle is fired the barrel will vibrate or rather oscillate. The goal is to have the right charge to have the bullet exit the barrel when this oscillation is closest to the barrel axis (not at the extreme limit).

So a node is the point where the bullet leaves the barrel exactly at this point of least deflection. Since the barrel is oscillating several times in the span it takes the projectile to start moving until it exit’s the barrel you could have situations where less powder may cause the bullet to exit say on the 4th barrel oscillation cycle but more powder and a faster velocity might have the bullet leave the barrel on the 3 oscillation cycle. These timed occurrences are nodes.


I also wanted to go back to your initial question about bullet seating depth. Since one of your use cases is 3gun and you will load for two firearms, I would just stick with the SAMI seating depth spec. At those close ranges I don’t think you would see the benefits precision seating.


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Makes sense, I will try sticking with saami spec. Thanks!