Load Development Using Chrono Velocity Ladder
- Thread starter CharlieNC
- Start date
CharlieNC
Gold $$ Contributor
Unfortunately cannot answer without the data! Based on the SD and sample size, this would need to show that average is not different from its neighbors to be a "node". Or assume a nominal SD based on past experience to determine the sample size.
Just an interesting note while working up with a chronograph:
I run all of my loads over a chronograph. Earlier development was shot over an Oehler 35P and the last few years I used a LabRadar. I shoot all of my stuff at the 400yd line which is actually 417yds.
Something that I've noticed on several occasions, some of my tightest groups had lousy SDs. And conversely, groups that had SDs of 3 or 4 were rarely the tightest at the 400yd line. You would think that high SDs would really show themselves at 400yds but it sure isn't always the case.
I run all of my loads over a chronograph. Earlier development was shot over an Oehler 35P and the last few years I used a LabRadar. I shoot all of my stuff at the 400yd line which is actually 417yds.
Something that I've noticed on several occasions, some of my tightest groups had lousy SDs. And conversely, groups that had SDs of 3 or 4 were rarely the tightest at the 400yd line. You would think that high SDs would really show themselves at 400yds but it sure isn't always the case.
Jager
Gold $$ Contributor
I love chronographs. I have long said that they have revolutionized handloading. I use mine extensively, considering it essential to my load development.
That said, I think the notion that chrono ladders and similar load development methodologies that hinge on ES, SD, and muzzle velocity stats rather than results downrange is... well, let me just say that I don't see it in my own fairly extensive data. Sometimes nice chrono stats marry up with nice results downrange. Often as not, they don't.
I understand the attraction. It's really quite seductive. Rather than all the hard work - the bench manners and the wind flags and the rifle craft and the knowledge that EVERY SINGLE SHOT shot counts... and that anything less than your A-game means that this ladder you're sending downrange becomes worthless - how nice would it be if we didn't have to worry about all that shooting stuff, and just let the chrono spit out what to do and where to go?!
Beyond a certain point, all this gets really hard. Loading truly high-grade ammunition and then realizing the potential of that ammunition in a high precision rifle requires an almost arcane level of dedication and commitment. I don't think there's an EASY button. Just the old school admonition to put in the work.
That's just been my experience. YMMV. My hat's off to anyone who finds a genuine short cut.
That said, I think the notion that chrono ladders and similar load development methodologies that hinge on ES, SD, and muzzle velocity stats rather than results downrange is... well, let me just say that I don't see it in my own fairly extensive data. Sometimes nice chrono stats marry up with nice results downrange. Often as not, they don't.
I understand the attraction. It's really quite seductive. Rather than all the hard work - the bench manners and the wind flags and the rifle craft and the knowledge that EVERY SINGLE SHOT shot counts... and that anything less than your A-game means that this ladder you're sending downrange becomes worthless - how nice would it be if we didn't have to worry about all that shooting stuff, and just let the chrono spit out what to do and where to go?!
Beyond a certain point, all this gets really hard. Loading truly high-grade ammunition and then realizing the potential of that ammunition in a high precision rifle requires an almost arcane level of dedication and commitment. I don't think there's an EASY button. Just the old school admonition to put in the work.
That's just been my experience. YMMV. My hat's off to anyone who finds a genuine short cut.
plenty of info /some data
precision shooting guide, LADDER
20 shots, 0.2 grain steps, plot the velocity vs charge weight.
look for steps/plateaus
now shoot 3 shot groups from the steps, and then 5 shot groups from the bests of the 3 shot data...then work on fine tuning.
it may actually work. i just won a 600 yd match without having finished the fine tuning!
precision shooting guide, LADDER
20 shots, 0.2 grain steps, plot the velocity vs charge weight.
look for steps/plateaus
now shoot 3 shot groups from the steps, and then 5 shot groups from the bests of the 3 shot data...then work on fine tuning.
it may actually work. i just won a 600 yd match without having finished the fine tuning!
CharlieNC
Gold $$ Contributor
Given every charge weight has an associated SD an ES which is greater than the average velocity of it's neighbors, it is not viable to define a plateau based on one shot. Drawing a curve in such a case is termed over-fitting, with no statistical viability. That's why I'm asking if anyone has used a sufficient sample size for believable results.
no its not a given and most of it does not apply. the math involved to produce valid numbers is significant as in 1000 or more shots. sd and es are cute but in the number world we do not shoot anywhere enough for them to be valid. it is just REFERENCE DATA in our field .
the whole idea is to do the shooting and the chart...the math does not apply to our sport. it aint science, its a guide.
the idea is to get to a useful load, not wear out a bbl developing NUMBERS.
it works, but you stick the science
FWIW Ive not had a lot of luck finding loads by looking for flat spots or chasing low SDs, I normally use three shot groups at 100 yards, going up on the load 2 tenths at a time. I want to see where the gun starts shooting and where it stops. I note the “velocity window” (for lack of a better term) and how big it is. Depending on the barrel it can be as narrow as needing to shoot right on the number or 40 or more foot wide. Keep your gun inside the window it will be competitive. Proper seating depth will give you the widest window. At short range I don’t worry with ES. For long range I like to keep ES no greater than 15fps.
This is an example of an exceptional barrel.
Bart
This is an example of an exceptional barrel.
Bart
This may cause a shit storm of respones, but I had to opine. @CharlieNC, if you are using good components and barrel, a one shot ladder will get you close. If not, or if your brass prep skills are sub-par the one shot ladder will leave you chasing your tail.
ES/SD are extremely important (assuming you care about ranges 600 yards and beyond!).
Assuming you are using quality components, and quality barrels (which is all that I have shot), the mathmatics of using chrono data helps a ton. Let me explain further.
1. In a powder ladder test, I have found that a low ES/SD identifies where the barrel is the most stable. (I don’t actually care about impact on target at this point)
2. Once I find the powder load I then move on to seating depth, which tightens the group considerably. I typically start at the lands and move back in .003 increments. In my chambering (.284) my best results show up between a jump of .012 and .027 from the lands.
3. I then sort bullets base to tip so that I can tip them accordingly.
Summary for long range shooting.
1. Stable powder/barrel = accuracy
2. Fine tune seating = precision
3. Tipping bullets = precision at long range
These are just my results over 25+ barrels in the same chambering over the last 5 years.
DC
ES/SD are extremely important (assuming you care about ranges 600 yards and beyond!).
Assuming you are using quality components, and quality barrels (which is all that I have shot), the mathmatics of using chrono data helps a ton. Let me explain further.
1. In a powder ladder test, I have found that a low ES/SD identifies where the barrel is the most stable. (I don’t actually care about impact on target at this point)
2. Once I find the powder load I then move on to seating depth, which tightens the group considerably. I typically start at the lands and move back in .003 increments. In my chambering (.284) my best results show up between a jump of .012 and .027 from the lands.
3. I then sort bullets base to tip so that I can tip them accordingly.
Summary for long range shooting.
1. Stable powder/barrel = accuracy
2. Fine tune seating = precision
3. Tipping bullets = precision at long range
These are just my results over 25+ barrels in the same chambering over the last 5 years.
DC
jelenko
Gold $$ Contributor
^^^^
Ccrider
Gold $$ Contributor
So,I must be the only one wondering. How did you initially choose the load to go with long distance and what actually ended up working.
My guess is 30.2.
HTSmith
Silver $$ Contributor
Wow is all I can say. How do you pick a charge when they are all so good? N133? Avengers? Dominators? Thanks for sharing.
Clancy
Silver $$ Contributor
There’s not anything left for me to say that hasn’t already been covered. The great equalizer is and always will be holes in the paper, BUT a chronograph is a handy tool.
I use mine when working with components I know little about, to keep myself from over pressuring a load. I also double check my node with it AFTER I’m done tuning. I still consider group size to be of greatest importance, like anyone.
I use mine when working with components I know little about, to keep myself from over pressuring a load. I also double check my node with it AFTER I’m done tuning. I still consider group size to be of greatest importance, like anyone.
That’s a 6ppc I’m getting ready for the IBS Nationals. The load will be different when I get there, but the window will be the same.
Bart
That was a 6PPC with 133 and Avengers. I’d probably go with something on the other side of the vertical group.
Bart
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