Ran some ladder tests today

[TexasMac]

Hey guys,

I made it to the local range today to run some ladder tests on a new rifle chambered in .45-70. I’d rather run the tests at longer distances but unfortunately the range limit is 200yds. There was some cross winds but not too bad, maybe 5-7mph. Following are the results. The yellow tape is covering old holes. 5 shots were fired prior to starting each test. The bore was wiped between shots. Pick what you think is the best load from each target. I'm leaning towards shot 6 on target 1 & either 5 or 6 on target 2.

Wayne

[bruce m]

4,5,6, and 7 looks like a node on target 2.
10,11,12,13,14 and 15 also looks like a good place to be in the middle of too.
further shooting will verify.
sometimes your group of 1 load has more vert than the whole node in the ladder.
so many factors.
11 to 16 might be a bit of a node on target 1 as might be 5,6, and 7.
bruce.

[Trusty Dog]

I apologize, but can you explain the concept of ladder test. What are we looking for? I’m used to looking for traditional grouping for consistent loads. Thank you. Jon

[Trusty Dog]

I did not explain my question very well. I understand that in a ladder test you are trying different levels of powder. I'm used to firing 5 or 10 shots for each of those levels of powder to see how the various loads group. I'm not sure I understand the targets in this post and what they tell you after only one or two shots at each powder level. Thank you, Jon

[SSShooter]

Jon - think you understand a ladder test the same way I do and have always shot them and, like you, am confused by Wayne's targets. 5-shot or 10-shot group with each load on a target and then the same with the next load. Windage doesn't count that much unless in a no-wind or very consistent wind condition. One is primarily looking at the tightest vertical grouping.

Perhaps Wayne's method is a place to start and then fine-tune between, say 67.5 to 70 gr of powder?

[SSShooter]

OK........ now I understand (I think):
https://www.6mmbr.com/laddertest.html
Looking for the 'node'. Once the node is found, then fine-tune within the node.

Have always thought I had enough load info to know where the node lies and started with the fine-tuning part. But, there is a reasonable chance I do not. Think I'll shoot a wider range (like Wayne) of loads and see if I've missed the node. If we ever are allowed to shoot again. Hopefully in a couple of more weeks. We should be peaking on infections this week, if not all ready.

[TexasMac]

4,5,6, and 7 looks like a node on target 2.
10,11,12,13,14 and 15 also looks like a good place to be in the middle of too.
further shooting will verify.
sometimes your group of 1 load has more vert than the whole node in the ladder.
so many factors.
11 to 16 might be a bit of a node on target 1 as might be 5,6, and 7.
bruce.

Bruce,

I agree with you on target 2 & plan to use shot 6 (59.5gr) & either shot 12 (62.5gr) or shot 13 (63.0gr) for further testing at longer distances. Target 1 is much less conclusive in identifying a node, but will likely pick shot numbers, 6 (69.0gr) & either shot 12 (72.0gr) or shot 13 (72.5gr) for further testing.

BTW, when comparing the compression range of shots on targets 1 and 2 there seems to be a discrepancy since each additional grain of powder should increase the compression by approximately 0.020". The approximation is close on target 2 but off on target 1. Due to the nose profile & 1st band location the PJ money bullet seats much further out of the case to contact the leade. Rather than use a higher range of powder 2 wads were used for shots 1, 2 & 3 to take up the space.

Wayne

[Trusty Dog]

Glenn, thank you for the explanation and the article, now I understand. Very helpful. I may try the same thing with both of my Sharps. One difference, it appears Bruce is shooting greasers and I'm loading and shooting PP's. There seems to be a lot more variations to play with when working up a PP load, i.e, number and placement of wads and lube cookies, bullet depth to the lands, amount of compression, etc. Again, thank you. Stay Well. Jon

[Kurt]

The ladder load testing finding the vertical node can be done with just 2-3 shots fired and improved after repeating and confirming the best 2-3 shot tests. Shooting 5 or 10 shot groups is good for trigger time but your throwing in a lot of variables that will change the results your wanting to get.
If you want to get the best out of your ladder load start with the cases. Exact inside volume being exact. Uniform case neck wall thickness. Barrel placement on the rest.
These are the largest contributor for verticals. Uneven bullet release do to uneven neck tension. Inside case volume changes the compression. Barrel placement increases/decreases the muzzle jump. Ignition is another factor.
Get your brass uniform and run the ladder tests. All you need is two or three shots fired to let you know what a good load is then take the best results to a long range.

[TexasMac]

The ladder load testing finding the vertical node can be done with just 2-3 shots fired and improved after repeating and confirming the best 2-3 shot tests. Shooting 5 or 10 shot groups is good for trigger time but your throwing in a lot of variables that will change the results your wanting to get.
If you want to get the best out of your ladder load start with the cases. Exact inside volume being exact. Uniform case neck wall thickness. Barrel placement on the rest.
These are the largest contributor for verticals. Uneven bullet release do to uneven neck tension. Inside case volume changes the compression. Barrel placement increases/decreases the muzzle jump. Ignition is another factor.
Get your brass uniform and run the ladder tests. All you need is two or three shots fired to let you know what a good load is then take the best results to a long range.

Kurt,

I respectively disagree but possibly do not understand the point you're trying to make? Certainly all the factors you mention contribute either negatively or positively to the accuracy of any load and to the test results, but to find 1 or 2 nodes for further testing requires many shots with a wide spread of powder/compression. For example, if I had only shots 1, 2 & 3 on target 2 to go by the node produced by shots 4, 5, 6 & 7 would not have been identified.

Wayne

[Kurt]

Wayne,

I don't have the gift you and a lot of other's writing on here have I should have carried it out farther and better. Your right about changing the amount of compression and I should have made that clearer.
What I'm getting at is your cases have to have the same inside volume so you don't get uneven pressure driving the bullet harder as well as having the consistent neck pressure.
When I work up loads I have a box of 60 plus cases that have the same inside capacity as well as uniform case necks and smallest diameter as well as demurred uniform flash holes. Using water to measure the inside volume is not a good way because you never get all out of the case, you need a very fine media that does not need compression. I shoot my tests from zero compression to maximum 3 rounds each, most of the times I only use a two round each ladder.

Wad stacks and bullet alloy makes probably the largest change in vertical because the loss of pressure behind the bullet before it clears the muzzle. . If you don't get the gas seal shot to shot you will see the verticals expand.

I guess all of this started when I was involved with HP bench rest and it carried into getting match grade loads using black and cast bullets now.
Mostly I just dump powder in the case using my old Redding or Lyman 55 powder drop and get just about but not quite the accuracy than using the uniformed cases, but I have them so I use them besides I enjoy the time behind the buttplate

Sorry for the confusion before and now. .......Kurt

[TexasMac]

Kurt,

Thanks for the clarification. Since the thread was only about the ladder test I did not go into the details about how I prepare and load cases to minimize the vertical spread due to variations. So far I have not sorted by volume but, realizing it may be a factor, one of these days I plan to run a ladder test to see if I can detect the effect of volume changes. I do insure the case neck walls are uniform by either turning the necks or by using a swaging process. I also trim cases to identical lengths, deburr the flash hole and anneal the necks after each firing.

I know that some shooters index their cases and bullets but I'm not convinced of the benefits of either for BPCR. But these are a couple of additional tests that one could run using the ladder technique.

Wayne

[SSShooter]

Sorting by volume can be quite laborious. Weight-sorting is much faster/easier and likely good enough for most shooting, other than Schuetzen benchrest.

[TexasMac]

Sorting by volume can be quite laborious. Weight-sorting is much faster/easier and likely good enough for most shooting, other than Schuetzen benchrest.

Good point Glenn. Thanks. Just so everyone reading this understands, Glenn's referring to sorting empty cases by weight not measuring powder by weight or volume.

Wayne

[TexasMac]

I made it to the local range today to further test some of the promising loads from the previous ladder test. The conditions were just about perfect. Hardly any wind. No cross wind, some at 6:00 but very little. Temp. ranged from 90 to 95 degrees with 70% humidity. The following photos speak for themselves. With the obvious exception of the very nice 59.5gr PJ Creedmoor pattern, what was somewhat of a surprise was the horizontal spread of the others with no cross wind. I sure hope the 59.5gr PJ Creedmoor load holds up at longer ranges. You can't ask for much better than that at 200yds.
We'll see since Yaupon Creek has decide to hold a match this coming Sat.

Wayne