Ladder test vs velocities

[Vandy321]

I know a ladder test will show best at 200+ yards.

However, based on weather and time, I plan to shoot at an indoor 100 yard range tomorrow.

If the 10 round ladder test us looking for the vertical flat spot, and 99% of the time that correlates with the flat spot in velocity over a chrono......why not just shoot it at whatever range you can and use the chrono data? Arent velocity flat spots and a flat spot in vertical stringing basically identifying the same node?

 

[FLS]

Yes. .2 Grain increments and look for the flat spot.

 

[bitbckt]

Vertical stringing happens _because_ of changes in velocity - they're measuring exactly the same thing.

 

[Vandy321]

I understand why it happens, but given that, why do folks put so much emphasis on "seeing" the results on paper, when graphing the chrono data and graphing the shot data (measuring vertical distance from POA to POI for each charge weight) from any range would lead you the same node

Meaning that is can be shot at 100 with the exact same results as 500, in that velocities wont change. But every thread I find in the internet says it needs to be shoot past 200 at a minimum.

Just figured I was missing something.

 

[Newtosavage]

Not everyone has a reliable chrono on hand. I'm a very visual person, and although I do have a chrono, I like cutting out that ladder test and taping it in my reloading book for reference later. Gives me more info, faster, than a velocity table would. But velocity tables are reassuring. I admit that.

 

[bitbckt]

Before the advent of affordable, available chronos, stringing and grouping was the only way to find a node. Those ideas still work just fine, and remain popular for the reasons @Newtosavage gave.

I put velocity tables in my reloading books. Call it "new math", I guess.

 

[Newtosavage]

Actually, I started writing the velocities at each hole on the ladder test, so I get the best of both worlds with a very quick look.

 

[FLS]

The farther you distance the more obvious the results. But it’s a trade off. Atmosperics and shooter error are magnified.

 

[Pro953]

Also. Latter tests are simple assuming your shooting positions and fundamentals are in place. A chrono is another mechanical device open to failure. I would also say that folks are not always the best at interpreting statistical data.

I know when I look at chronograph data I tend to want the node to be higher than it is at times. My motivations and wishes can cloud the data so I look for the results a want in the data. I find that a bit harder when looking at groups holes on paper. Especially if I can repeat the test a few times.

For me one of the hardest lessons I am learning as I work on my reloading skills is trusting what the rifle/target are telling me and not what I read or think should happen.

Reading some of the Litz books has been helpful on this front.


Sent from my iPhone using Tapatalk

 

[Vandy321]

A few on LRH are suggesting i shoot this again out to range I intend to shoot to and that 100 yard ladder test isnt valid?

I shot this inside at 100 to eliminate variables like temp swings, fatique (from the heat), wind, etc.

What says the rokslide?

300wm, 26" proof, berger 215s, H1000

I'm thinking shot 6, 7, 8....76.5 to 77.5 is my high node. That seems to line up with everything I've seen Broz post as far as 215s/H1000

Next up seating depth test at 77gr or shoot groups inside of node to confirm?

 

[FLS]

Load from 76.5-77.5 in .2 gr increments. You should see the velocity level off . That will give you the middle of your node. 77 is probably the middle. Then play with seating depth to tighten groups.

 

[bhylton]

i would just load a few at 77, see if the group holds and quit wasting components.

but then again, im not going to chase 15fps more velocity or try and take .1in off my groups..

 

[WestexSBK]

Shooting at distance will highlight other variables that need tuning. Neck tension, seating depth, bullet stability. You can mistake statistics. You can’t mistake what happens on paper.

You were given very good advice on LRH. A ladder test should be done at 300+. A tiny group at 100yds can and will fall apart at distance. A mistake many reloaders make.

My last 6.5x47L Barrel shot 130vlds .5moa at 100yds and consistent .3moa at 600yds. Riddle me that. It happens all the time

Joe

 

[Vandy321]

Shooting at distance will highlight other variables that need tuning. Neck tension, seating depth, bullet stability. You can mistake statistics. You can’t mistake what happens on paper.

You were given very good advice on LRH. A ladder test should be done at 300+. A tiny group at 100yds can and will fall apart at distance. A mistake many reloaders make.

My last 6.5x47L Barrel shot 130vlds .5moa at 100yds and consistent .3moa at 600yds. Riddle me that. It happens all the time

Joe

While I would like to do a bunch of testing, it's not a BR gun, It's a 300wm and berger 215s, strictly for hunting, its been done a million times. I'm not planning to burn 200 rounds trying neck tension, 5 primers, 18 seating depths, 5 shot groups at .2gr. Etc (well, maybe this winter ). Its a hunting rifle, the flat spot in the velocity node is all I'm looking for, temp stable load with good OBT, if I can tweak seating depth to hold shoot sub MOA at 700, I'll be happy. Single digit ES is the goal.

I politely disagree that a latter test looking for the velocity flat spot (satterlee) needs to be shot at 300 to be valid. To each his own. The paper and the chrono both verify the node. Yes, shooting at distance will show a taller string making it easier to see, but it will not change FPS, harmonics, OBT.

Planning to load up 77gr, shoot 10 for SD...then seating depth test at 300 yards for groups.

If it doesnt group well or hold single digit SD...I'll try another ladder.

 

[dgarrett]

I would work around your 6 and 7 load.... When I use the chrono I am also paying close attention to extreme spread between the loads... If I only get say a 7-15fps spread between 2-3different powder charges... This should theoretically show a node... A lot of .300 wins will show pressure at 77gr.. or close....My go to load that has worked in a few of the .300's is 76.4gr H-1000 with cci 250... 2.849 to ogive with the 215 bergers... at 2908fps and 4fps extreme spreads in the last rifle I worked up... These rifles were all chambered with the reamer mentioned as a good one on LRH site... Dave

 

[Vandy321]

My concern is 6 is the bottom of the node (maybe). And with temps at 80-90 degrees here during load dev, even with temp stable H1000, I'm worried that cold weather 10's/20s during a hunt may drop me out the low end of the node.

Planning to work around 77 after I test some seating depths tomorrow at longer range.

Had no pressure until 78.5 with a flattened primer (no cratering though) and no sticky bolt. I stopped there. 77 was gtg.

 

[tyeager2964]

I agree with your argument thus far. The one aspect that is missing from doing a ladder test once at a hundred yards is that one data set doesn't equal any amount of statistical validity. Doing one ladder test at 300 or 700 won't either. For that matter one 3 shot group at 100 yards during OCW testing isn't statistically valid either.

In my opinion all a ladder test does is give you a starting point that can then be further refined. In a vacuum one test at 100 yards should give you the same results as one test at 1000 yards. Unfortunately we don't live in a vacuum and further testing will be needed.

I would probably do the same as you but start at 77.2 and see what happens. The only reason I suggest 77.2 is that when you start at 77 your es to 76.5 and 77.5 is 13 and 12 respectively. If you start between your two known data points your ES will likely be 6.5 up or down. Either way you will need to shoot groups to confirm.

 

[Vandy321]

I agree with your argument thus far. The one aspect that is missing from doing a ladder test once at a hundred yards is that one data set doesn't equal any amount of statistical validity. Doing one ladder test at 300 or 700 won't either. For that matter one 3 shot group at 100 yards during OCW testing isn't statistically valid either.

In my opinion all a ladder test does is give you a starting point that can then be further refined. In a vacuum one test at 100 yards should give you the same results as one test at 1000 yards. Unfortunately we don't live in a vacuum and further testing will be needed.

I would probably do the same as you but start at 77.2 and see what happens. The only reason I suggest 77.2 is that when you start at 77 your es to 76.5 and 77.5 is 13 and 12 respectively. If you start between your two known data points your ES will likely be 6.5 up or down. Either way you will need to shoot groups to confirm.

I do agree that the 77.2 (middle of a 12 fps sread between 77 and 77.5 is good. I loaded up 76.8, 77 and 77.2 and saw no real dif in groups, but did not run 77.2 or 76.8 over the chrono yet.

Should I be concerned that as this barrel breaks in, and speeds up, now that same 77.2 takes me towards the top and maybe out of my node?

I only ask because when I ran 77 over the chrono the other day seperately, I had already gained an average of 15fps (barrel then had 75 rounds on it)

Correct to assume though that at 80 degrees, it's best to find a load at the higher end of thar node, so that when temps dip in the mountains, that lower speed at worst drops me back to the middle of my node?

 

[tyeager2964]

The more data the better. Whether or not your harmonics change after break in and how much your barrel speeds up can only be determined by experience. In my experience quality rifles and barrels are more forgiving and I typically cant shoot well enough to tell if 0.1 or 0.2 MOA groups is due to the velocity difference on a given day, a multitude other variables, or myself.

I wouldn't be concerned at all. I would find a load you like and shoot it until it doesn't preform.

Eventually you will hit the law of diminishing returns and will have to decide if chasing that extra variable is worth it. That variable could be concentricity, temp stability, primer, bullet consistency, throat erosion changing your jump, etc. I typically am happy with 0.5 MOA and don't chase after that.

 

[mt100gr.]

I don't want to hijack this thread, but I am curious as to point of aim? Did you work from the 2 horizontal lines so holes (data) wouldn't overlap? I ask because 100 yards is the most convenient distance for me to make multiple trips to shoot.

Last spring I switched primers in my 300 WM (215 hybrids over H1000) and just ran a quick/simple pressure check before settling on a load. I never saw pressure at the top, but I settled on 76.5 grains based on some further grouping results.