ladder test for seating depth
- Thread starter bowzarrow
- Start date
In my rookie opinion the Ladder Test has no place in determining seating depth. I think the Ladder Test is all about finding the optimum velocity(s) for your barrel, and is probably the biggest factor in determining the optimum load. After finding the best velocity it make sense to determine the optimum seating depth. Seating depth will affect velocity so you have to consider that when determining optimum depth.
bozo699
Gold $$ Contributor
Yes I agree with RonAKA, use your ladder test to find your optimum charge weight.Then vary your seating depths to fine tune your groups.Seating depth is key to accuracy and I personally think this is especially true with the long vld style bullets. best of luck.
Wayne.
Wayne.
RonAKA is spot on... if you go from 'jammed' to 'jumped', or vice-versa, you've just changed velocity. It really can be a vicious circle, and you might get overwhelmed. Like I did!
My suggestion is to run 2 ladder tests first. Load one batch of rounds with the bullets jammed, and one with the bullets jumped. (for now, just pick an arbitrary amount, like .010" jam and .010" jump). Adjust the powder charge only with each batch, and shoot each of the ladder tests. This will show you the most accurate node with a jam and the most accurate node with a jump. Once that is complete, use the charge that worked best and shoot 2 more ladder tests, but adjust the bullet seating depth only. (just keep the 'jump group' jumped at various distances, and keep the 'jam group' jammed at various distances). Hopefully that makes sense?
That's the method that I feel will get you to the end result the quickest while testing as many variables as possible. This is one of those subjects that seems to have multiple answers, so take it all in, and do what you think will work for you.
Walt
My suggestion is to run 2 ladder tests first. Load one batch of rounds with the bullets jammed, and one with the bullets jumped. (for now, just pick an arbitrary amount, like .010" jam and .010" jump). Adjust the powder charge only with each batch, and shoot each of the ladder tests. This will show you the most accurate node with a jam and the most accurate node with a jump. Once that is complete, use the charge that worked best and shoot 2 more ladder tests, but adjust the bullet seating depth only. (just keep the 'jump group' jumped at various distances, and keep the 'jam group' jammed at various distances). Hopefully that makes sense?
That's the method that I feel will get you to the end result the quickest while testing as many variables as possible. This is one of those subjects that seems to have multiple answers, so take it all in, and do what you think will work for you.
Walt
I, also, am an amature in this field. But, here is how I attacked this problem;
First, I did a ladder test of charge weight , all with a fixed jump. I also used a chronometer and monitored MV and SD.
Next, using the best charge from above, I did an abbreviated ladder of jump in a logrithmic progression, 0,10,20,50,100, of jump in thous.
Next, from a plot of MV from the first test, I re-did the second test by modifying the charge to insure the same MV at each jump. This then yielded a jump that seems to work well for most any charge. I plotted the results of the modified jump ladder and interpolated for best jump. In my case it worked out to 0.040" at the MV with best group.
I'm sure there is a residual error, but I'm happy.
First, I did a ladder test of charge weight , all with a fixed jump. I also used a chronometer and monitored MV and SD.
Next, using the best charge from above, I did an abbreviated ladder of jump in a logrithmic progression, 0,10,20,50,100, of jump in thous.
Next, from a plot of MV from the first test, I re-did the second test by modifying the charge to insure the same MV at each jump. This then yielded a jump that seems to work well for most any charge. I plotted the results of the modified jump ladder and interpolated for best jump. In my case it worked out to 0.040" at the MV with best group.
I'm sure there is a residual error, but I'm happy.
If you jump or jam the bullet then adjusting the seating depth through a ladder test is a good way to fine tune your load. Going from jump to jam will cause a pressure /velocity spike as the others have mentioned but as long as you are only doing one it works fine.
Even going from jump to jam the ladder test is a good tool to validate your load. Obviously if a load shoots better under different setting then you haven't got the tune right.
Even going from jump to jam the ladder test is a good tool to validate your load. Obviously if a load shoots better under different setting then you haven't got the tune right.
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