Thread: 440m ladder test

Originally Posted by marky123

If you discount shot no.1, 9 bullets from cartridges loaded with a 1.8 grain different charge weight went into 4.5”.
Bullets 3,4 and 5 went into 2.25”.I think thats good shooting at 440m from a factory B14.We are loading for accuracy not speed,its a hunter.
We will repeat the ladder with 6 from 40.6 to 41gn and report back.

Ok, so you are pretty much focusing on "group size". Although as John pointed out above, groups of 1 kinda mean zip.

I would suggest you look at the speeds. Assuming of course you have a reliable and repeatable chrony.

Shots 5,6,7,8 are all within single digit ES from each other. It looks like a likely node in this ladder. Having said that, I would much rather look at SDs for 5 shot groups, the more data you put in the better the quality of the info you get out...

If (and it is a big IF), that is a node, then I would look at choosing a load in the middle, and playing with different seating depths. Shoot at least groups of 5. Do it at 100m and make sure the wind is not affecting group size.

Originally Posted by ebf

Ok, so you are pretty much focusing on "group size". Although as John pointed out above, groups of 1 kinda mean zip.

I would suggest you look at the speeds. Assuming of course you have a reliable and repeatable chrony.

Shots 5,6,7,8 are all within single digit ES from each other. It looks like a likely node in this ladder. Having said that, I would much rather look at SDs for 5 shot groups, the more data you put in the better the quality of the info you get out...

If (and it is a big IF), that is a node, then I would look at choosing a load in the middle, and playing with different seating depths. Shoot at least groups of 5. Do it at 100m and make sure the wind is not affecting group size.

As far as I understand,a ladder test is the relationship between POI and velocity.If unsuitable powder charges are used then they are nowhere near their next or previous.If it is,then they are closer together,hence 3,4 and 5 are suitable charge weights in this instance.Further testing with those charge weights will prove or disprove that.Happy to be proved wrong.

Originally Posted by marky123

As far as I understand,a ladder test is the relationship between POI and velocity.If unsuitable powder charges are used then they are nowhere near their next or previous.If it is,then they are closer together,hence 3,4 and 5 are suitable charge weights in this instance.Further testing with those charge weights will prove or disprove that.Happy to be proved wrong.

https://www.6mmbr.com/laddertest.htm...%20of%20primer.

SUMMARY: Repetitive, round-robin Ladder Testing with multiple charge weights can reliably identify those loads which deliver minimal vertical dispersion at long range. ... While the Ladder Test method is primarily used to divine optimal charge weight, it can also be used to find the best seating depth or brand of primer.

Originally Posted by marky123

As far as I understand,a ladder test is the relationship between POI and velocity.If unsuitable powder charges are used then they are nowhere near their next or previous.If it is,then they are closer together,hence 3,4 and 5 are suitable charge weights in this instance.Further testing with those charge weights will prove or disprove that.Happy to be proved wrong.

Yup, but you are shooting single loads. How can you be sure the vertical dispersion is due to the load and not due to your shooting.

That is why I keep stressing 5 shot groups. If you can show me 5 shots of the same load, all on the same vertical plane, then I will be convinced.

The correlation between increasing load and increasing velocity is not completely linear.

The target you posted has vertical all over the place (some of the slower loads land higher etc), so it does not really show much. If you were shooting a whippy hunting barrel, that may have been due to harmonics causing the projectile to leave the muzzle at different points in the whip, but then you would struggle to shoot accurate groups at most time.

All things working well, you would expect to see poi climb as the charge weight increases. Where that climb becomes contracted for equal increases in charge, is likely to be a node. I am not seeing any of that on your target (based on poi)... I do however see a potential node if you look at the speeds.

2 questions:

1) what chrony are you using ?
2) rifle ? particularly barrel profile ? is it a noodle or something a bit more beefy like HMR ?

Originally Posted by ebf

Yup, but you are shooting single loads. How can you be sure the vertical dispersion is due to the load and not due to your shooting.

That is why I keep stressing 5 shot groups. If you can show me 5 shots of the same load, all on the same vertical plane, then I will be convinced.

The correlation between increasing load and increasing velocity is not completely linear.

The target you posted has vertical all over the place (some of the slower loads land higher etc), so it does not really show much.

Assuming the chrony and the shooter (not me) were working correctly and the conditions were good (there was no readable wind) then the test shows less POI dispersion and velocity between some shots to others.
You can reasonably presume that those charge weights are ‘good’ loads.We will then repeat the ladder test hopefully under the same conditions with a smaller variance of charge weights at the same distance.Hopefully some of those loads will be ‘good’.Then we will select a load and shoot groups with it to confirm.

If that works then we have found a ‘better’ load with 20 shots.

More charge weight is not linear with velocity,I haven’t said it is.
We will shoot some 3 or 5 shot groups but only when we have dialled in a ‘good’ load.