Ladder test and internal volume

[Boisblancboy]

Is there a good seating depth to do a ladder test if you plan on doing a seating depth test afterwords that would be from a .010” jam up to a .030” jump? Being that would change the internal volume a fair amount, especially on smaller cases, would doing more than one ladder test be of service?

 

[dmoran]

By starting ITL and working off (OTL), your also working away from pressure.
Myself and most I know do it that way. With that said, will suggest to start at your .010" or further ITL.

 

[Boisblancboy]

By starting ITL and working off (OTL), your also working away from pressure.
Myself and most I know do it that way. With that said, will suggest to start at your .010" or further ITL.

So just run the ladder test with the .010 jam/ITL? No need to run the ladder test at the other end of the spectrum, .030” OTL?

 

[dmoran]

Correct.... after you find the powder zone(s), then go after seating.
Then after nailing the seating down, you can go back and fine tune the powder charge, fallowed by fine tuning of the seating.

 

[std7mag]

And after seating depth, tune the action.

 

[bench]

And after seating depth, tune the action.

Some one please explain to me what this means
Thanks

 

[std7mag]

There was an article on this forum, that involves shooting groups, while changing the torque on your action screws.
Much like the seating depth procedure has the group size getting smaller then opening up, this just tells what the bullet likes.
When you adjust torque on the action screws, your groups will get smaller then expand. Or start off small and expand. Or get smaller.
This tells what the action likes.

And it can be a noticable difference in group sizes!

 

[bench]

There was an article on this forum, that involves shooting groups, while changing the torque on your action screws.
Much like the seating depth procedure has the group size getting smaller then opening up, this just tells what the bullet likes.
When you adjust torque on the action screws, your groups will get smaller then expand. Or start off small and expand. Or get smaller.
This tells what the action likes.

And it can be a noticable difference in group sizes!

Thanks understand now
Bench

 

[rsmithsr50]

I work hard at finding TOUCH. no jam.
and I work from there.
while backing up will decrease case volume, you have also
moved away from the lands which should counteract that.
once you have settled on a load, then test in and out of the lands for best.
once at best, retest either side of the powder load

 

[CharlieNC]

Or first define the seating depth at a moderate load, and ladder test powder next. Either way you should fine tune both together as the final step.

 

[JEFFPPC]

Thanks understand now
Bench

I, never cease to be amazed.

 

[R.Morehouse]

I would think if you start with the bullet jammed and climb the ladder till pressure you will have a good starting point.

Regards
Rick

 

[Spike A]

so i have a question with a wrench to throw in..... ive got a 22-250 with a 14 twist that im working on with a 45gr bullet... it will not touch the lands .. so i started out with a seating depth ladder .. than powder... which i am still working on/ waiting for the right conditions/ temperature... than ill go back to seating test... any other ideas im open too...

 

[Ned Ludd]

No load is going to show optimal behavior over the entire charge weight range during the course of carrying out a ladder test, pretty much by definition. That's the whole point of doing the ladder test in the first place. You're looking for at least two or three successive charge weights that essentially have the same vertical POI at some specified distance. That charge weight window indicates a region in the charge weight curve where velocity has minimal effect on vertical displacement, i.e. positive compensation. It can also be argued that loading to the middle of that charge weight window will cause the load to be less sensitive to modest changes in ambient temperature.

You could certainly do a coarse seating depth test at a slightly reduced (safe) charge weight first if it makes you feel better about the ladder test. But it's not going to change the way you interpret the results of ladder test. This is because the load will go in and out of tune as you carry out the test no matter what the seating depth, and also because you're shooting single shots at different charge weights, not multiple shot groups at the same charge weight. FWIW - when in doubt, I start a new bullet at .015" off the lands. You will hear others here that start them at what is essentially a hard jam and then work outwards. There are a variety of paths you can use and still end up at the same spot.