Please Give Opinion On This Ladder Test (Pics)

[vh20]

I need experienced opinions on this ladder test I ran today since I've never run one before. Any help would be appreciated. Here are the details on the specifics:

Rifle: Savage 110 FCP HS Precision, .338 LM
Load: Lapua brass, CCI 250 primer, Sierra MK 300 gr. bullet, Retumbo powder
Target Distance: 300 yds.
Conditions: 76 deg. F, Winds - Quartering-to-direct tailwind @ 12-13 Kts

I began at the Hodgdon-listed minimum load of 85.0 gr. and progressed in 1.0 gr. increments up to 88.0 gr, then, beginning with load #5 @ 88.5 gr, progressed from there in 0.5 gr. increments all the way up past the book-listed maximum load of 94.0, finally ending on 95.0 gr. No real evidence of excessive pressure was noted except for a slight bit of cratering around the firing pin indentation on the last 2 or 3 rounds (no primer flattening, no ejector marks, no hard bolt lifts, etc. were noted).

I'm not experienced with spotting nodes, but I'll throw out what I think I see on the paper, and ask for your advice on my interpretation. The first potential node I think I see occurs with loads 9, 10, and 12. Oddly, load #11 dropped to the bottom of the paper, and I can only guess I pulled it, but it felt good at the time. MVs for this string are as follows: 9 = 2633, 10 = 2672, 11 = 2663, and 12 = 2683.

The next potential node I think I see occurs with loads 13 and 14. There's a significant hop from 12 to 13, but then 13 and 14 fall within about 1/2 in. of each other vertically. MVs are 13 = 2698, 14 = 2727.

Finally , there appears to be another node @ 17 and 18. Both these loads are above the "book" max of 94.0 gr., with 17 @ 94.5, and 18 @ 95.0. MVs are 17 = 2785, 18 @ 2800. I also found it interesting that the lowest-power loads, and the highest-power loads landed on the same windage plane as the aimpont, while all others in-between landed to the left to varying degrees.

So, what to do with this info? The lowest node (9, 10, 12) falls a little below the MV level that I'd like to achieve, but seems to have some real accuracy potential. The middle node is about where I'd like to run (around 2700), but may not quite have the accuracy potential of the others. And finally, the upper node with the final two shots is potentially impressive, but I wonder if I'd be burning up the barrel and brass at an excessive rate running things that hot?

I'm really looking for advice on my next move. Any advice is much appreciated. I'm also posting this on the Long Range Hunting site for additional insight. Thanks!

 

[vh20]

Re: Please Give Opinion On This Ladder Test (Pics)

Anyone have some insight?
Thanks

 

[LawnMM]

Re: Please Give Opinion On This Ladder Test (Pics)

Do you have more chronograph data? What are your SD/ES numbers for different strings. Opinions vary so take this for what its worth. I personally believe that you should load off the chrono data. Some people don't trust them, to that I say buy a good one and verify it with a drop test if it helps you sleep better.

I say load by chrono because I believe it's the most objective method. You often have novice reloaders who are also novice shooters trying to base their loading off of group size, or worse yet, a single loaded round at a given powder charge.

Realize the variables involved in all this and run five rounds at a given charge, minimum. Ten would be better. While some loads group better close than at distance I've yet to see a load with single digit SD numbers group poorly in capable hands at any range.

With regard to your specific testing, a whole grain is a pretty large increment, so is half a grain. Its fine for getting close but when the chrono shows tighter numbers around say 92gr I'd go up 0.3gr and down 0.3gr in 0.1gr increments to really zero in on the tightest numbers possible. When you have that done, shoot for group size at 300 and 500 and I doubt you will be disappointed. See if the drop you see IRL matches what the ballistics say for your MV and that will tell you how accurate your chrono data is.

Pulling round 11 is what I'm talking about, you say it felt good but it's way low. So either you yanked one, or something was off in the reloading process. Variables that skew and invalidate the visual approach (where did the rounds land) to reloading. If you shoot a string of 5 or 10 now you can look and say hmm there's a lot of vertical dispersion at 90gr. Which will likely correspond to high SD/ES numbers. Its really hard to judge off 1 or 2 rounds because the changes can be attributed to so many variables.

If 11 and 12 are where you want to be with MV start shooting strings of 5 or 10 around there and check your SD/ES numbers there. Then add 0.2gr and subtract 0.2gr and see if the numbers improve. If adding 0.2gr makes it better, try another 0.2gr, when the numbers stop improving, drop to 0.1gr increments and whittle that SD down to single digits.

If it doesn't group well with a single digit SD that should show next to no vertical dispersion I'll eat my hat.

Rich

 

[vh20]

Re: Please Give Opinion On This Ladder Test (Pics)

I don't have the chrono numbers with me (at work) but I'll gladly post them tonight if you don't mind checking back in (actually, I may can get those at lunch). I didn't see a "tightening-up" of the chrono numbers around a node like I was expecting, but maybe I'm just not seeing it. By the way, if you mean numbers for multiple rounds of each load, then no, I don't have that. This is my initial ladder test, and only one round of each load was used, with the exception of a few foulers/sighters I brought along.

The 1.0 grain increments were only used at the bottom of the range, where I figured MVs were lower than what I was looking for. I loaded them more to check for pressure signs.
Thanks for your help - I'll get the rest of the numbers up.

 

[vh20]

Re: Please Give Opinion On This Ladder Test (Pics)

LMM, here's all the data I have:

1) 85.0 @ 2508
2) 86.0 @ 2527
3) 87.0 @ 2530
4) 88.0 @ 2577
5) 88.5 @ 2583
6) 89.0 @ 2601
7) 89.5 @ 2615
8) 90.0 @ 2621
9) 90.5 @ 2633
10) 91.0 @ 2672
11) 91.5 @ 2663
12) 92.0 @ 2683
13) 92.5 @ 2698
14) 93.0 @ 2727
15) 93.5 @ 2771
16) 94.0 @ 2771(*Hodgdon's Max.)
17) 94.5 @ 2785
18) 95.0 @ 2800

 

[LawnMM]

Re: Please Give Opinion On This Ladder Test (Pics)

Ok, so you want to be around 2700fps. Nothing you have done so far is wrong, and you're on the right track. Do you understand what I was saying about number of shots in a string and their statistical significance?

Shot #11 is a good example of why I'm saying when you start trying to narrow this down, you need to burn about 5 shots in a string, minimum. It's almost 10fps slower than shot #10 and 20fps slower than shot #12 despite having a half grain more powder than #10 and only a half grain less than #12.

There's about a dozen things that could cause that, I'm not going to speculate which one is to blame because it isn't important yet. I just want to illustrate the point. Now that you're ready to narrow things down, and you don't have any pressure issues to speak of, it becomes more important.

If it were me, I would load 5 rounds at 92.5gr, 5 @ 92.7, 5@ 92.9, 5 @ 92.3 and 5 @ 92.0

Run all five at each charge over the chronograph in sequence. You want the chrono to give you a nice set of data for average speed, standard deviation, and extreme spread on each charge. 10fps and lower is the golden goose of reloading.

If 92.5gr gets you an SD of 27 and 92.7gr gets you an SD of 19 then the 92.5gr you started with is just BELOW an accuracy node. The opposite is also true. Without good SD/ES numbers you can't really start zeroing in on an accuracy node. You may try 92.9 and get an SD of 15 and then you're back to an SD of 23fps at 93.1...see where this is going?

If the numbers start opening up again you're on the other side of the node, you then need to go back to say 92.7 and move up in 0.1gr increments to really zero in on the single digits. Make sense?

What you've done so far is good, its what I will typically do when switching projectiles or trying new powders. Its a good way to check for pressure initially. However, you're trying to draw conclusions from it that you don't have enough data for at this point. You're headed in the right direction, you just have to narrow things down now that you know where you want to be.

What kind of chrono are you using?

Rich

 

[vh20]

Re: Please Give Opinion On This Ladder Test (Pics)

Rich,
I definitely understand your point of the significance of strings. I'm just having trouble deciding which loads are the ones worth testing further (with either groups, or as you suggest chrono-strings). I really wasn't trying to draw any conclusions from it other than where to focus for the next test. Your last post is a big help in that regard. Where I would probably pick some of those loads and shoot for groups, your method of using the chrono as the guide is a different approach for me.

You mentioned running tests around the 2700 fps mark. What do you think of the ones in the upper range (i.e. with shots 15-18, you have 4 progressive loads that have an extreme spread of only 29, whereas there's a 44 fps jump just between 14 and 15 alone)? I'm a little concerned about running above the "book" max, just because I've never done it in the past. Here's a pic of some of the brass. 85.0gr. on the left, 90.0 gr. in the center, and 95.0 (my hottest) on the right. There is slight flattening and cratering compared to the lightest, but not that much. What do you think:

As for the chrono, I'm afraid all I have is a Shooting Chrony Alpha.
I really appreciate you taking the time to respond, Rich.

Jim

 

[LawnMM]

Re: Please Give Opinion On This Ladder Test (Pics)

You have what looks like ejector wipe to me on the APU of Lapua on the 95.0gr brass. That circular shiny spot that looks like somebody took an eraser head and wiped it around the edge of the case head is a sign of over pressure. You'll usually get that prior to the bolt lift getting sticky. Its a sign you're already over where you should be at 95.0gr

Don't get overly concerned with loaded at the upper end of the spectrum. Load for accuracy, not speed. A faster round with a wide ES will cause significant vertical dispersion at long range.

I know the "Let thy Chrono be thy guide" is a new approach, but I'm going to continue advocating it until somebody shows me a load with tight SD/ES numbers that doesn't group well. Its not that everybody isn't a good shot, its that a lot aren't as good as they think. Sometimes you have an off day. Sometimes you haven't shot for a while. My consistency drops way off when I haven't shot in a while. Its a perishable skill and guys are putting way to much emphasis on group size, which is subject to a wide range of variables.

The chrono doesn't lie, and it doesn't care if you're tired, happy, sad, a good shot or a shitty one. The math doesn't lie. If Mr. Chrono says that's a tight load, then you have something that will land consistently at the same point of impact at a given muzzle velocity and range. Wind is the shooter's problem.

Anywho, you also don't want to go straight for max pressure in case you should find yourself shooting in a warmer climate, you'll run into pressure issues. I think a good rule of thumb is, find where you start running into pressure signs, then look for the accuracy load immediately below the pressure indicators. You may have to tweak it farther if you work up a load in cold weather as things warm up, but you seem to be having good weather there so I wouldn't worry about the difference between 75 and 100. If you work it up at 30, leave yourself some room to expand as the summer approaches.

Is this the first firing on the brass? You have an ejector mark on the Lapu"a" and "m"ag on the 90gr case to by the look of the picture. I don't have any experience loading for this caliber or with this powder but 300 is on the heavy side for 338 isn't it? You may run into pressure earlier with heavy projectiles. I ran some 208 amaxes through my 308 and it showed up pretty early. Its hard to get the bigger bullets moving faster while avoiding pressure issues.

As for the chrono, if it gives you SD/ES and AV that's what you really need. As far as running above book max, eh, I wouldn't worry about it in the absence of pressure signs. All chambers are not created equal. Cratered primers aren't a great indicator because it can be a sharp or slightly deformed firing pin, or a heavy firing pin spring. Its not necessarily indicative of pressure problems. Ejector wipe is a bigger red flag, if your bolt is stiff and you're having to force it up, that's the biggie. You're approaching a problem at that point.

I don't want to burn up my barrel, nor do I want to over stress my chamber, so I advocate finding the first bit of ejector wipe, then go with the node just below. No undue stress on the gun, and it leaves you with some breathing room for temperature variations.

Rich

 

[vh20]

Re: Please Give Opinion On This Ladder Test (Pics)

Thanks. I didn't intend to give the impression I want to load for speed. Speed is great, but I'm pretty happy around 2700 if I can get the best accuracy there - should be better brass and barrel life. What drew me to the max loads was actually your criteria - they have by far the LEAST spread in the MVs, plus (except for 16) they were extremely tight vertically. Take a look again at those shots and MVs - do you think there's anything there?

This is brand new brass, first firing. 300 gr. is the upper limit for 338LM that I'm aware of, but it seems to be fast becoming the most popular choice. I'm not familiar with ejector "wipe," but I am familiar with/have seen ejector marks "imprinted" on over-pressured case heads before (not here though). Can you explain a little further? (Edit: Nevermind, I think we're talking about the same thing). Anyway, 300gr SMKs or Scenars appear to be working well for most folks, and Lapua makes a 300 gr. factory load that operates just over 2700. I'm going to go back and look at those specific areas you mentioned on the case heads and report back.

This chrono does provide SD, ES, and AV.

Edit: After close inspection of the case heads under magnification, I can't say I see much difference between the max load of 95 and the min load of 85. All heads have a slight shiny "ring" around them occupying the space between the primer perimeter and the inner diameter of the headstamp lettering. You can see it on all three of the cases in the pic, and all of the other fired rounds in the box (from my uniformer, believe?). I can see a faint shiny ejector mark on EVERY case under magnification if I look hard enough. Perhaps the 95gr load has a slightly more prominent imprint of the ejector, but it doesn't just stand right out. It is the only one that I can say might look different than any of the others, though.

Thanks, again!

 

[LawnMM]

Re: Please Give Opinion On This Ladder Test (Pics)

I think I may not have made what I'm saying clear and I don't want to lead you in the wrong direction. When I'm talking about tight numbers and low spreads in MV, I'm talking about multiple rounds at the same powder charge. Not the spread in mv between different charges.

When you fire five rounds at the same powder charge your chronograph will give you an average velocity for the five rounds. You will get an SD value based on how far each round varies from the average. The ES will give you the total difference between the slowest and fastest rounds.

Depending on barrel harmonics, how accurate your scale and reloading process, etc., are you will get different values at different charges. You will need a decent sample size of chronographed rounds at each charge to determine which works best.

You haven't posted any SD/ES info and I can only see two rounds in the paper with the target picture. I'm assuming its because you only fired two rounds, and your chrono may not even give you ES/SD with a string of two rounds.

Speed differences between different powder charges are somewhat irrelevant. You want consistency between rounds in the same string at the same charge. I agree I see little difference in vertical dispersion between two shots at each charge. What I'm suggesting is you not base your starting point on two rounds. I'm all for experimenting and having fun as you learn. If you think a certain charge has potential, load five and shoot a group over the chrono. When we compare 5 rounds to each other we will have a better idea of what the vertical dispersion really looks like and the chrono will give us SD/ES data to compare to what we see on paper. I apologize if I'm misunderstanding you and for any spelling/grammar on this post, I'm replying from my phone.

 

[vh20]

Re: Please Give Opinion On This Ladder Test (Pics)

First off, I am impressed you can type that much from your phone! I'd never even attempt it! And no need to apologize for anything - you've been more than patient.

No, I've been with you all the way about multiple rounds of the same charge. That was my plan all along, the only difference being that you are advocating putting more emphasis on the chrono data from those strings, whereas I had planned on shooting for groups and using the chrono data more to confirm/backup that there are consistent MVs with whatever loads grouped nice. That said, I'm very interested in trying it your way, and that's why I keep bending your ear (thanks, again).

So the question has always been "what loads to test further." Where we may be mis-communicatiing is in our use of the data from the ladder test I posted. I have been trying to use it as a guide to determine what loads to focus in on and shoot multiple-round tests on. I've never done one of these (ladder test) before, but my understanding is that you're looking for a group of incrementally-increasing loads that still group vertically together on the target, and ALSO MVs that don't have as much change between them as loads in other areas of the test that don't group as well. The only place that seems to occur on my data is loads 15 - 18, but they are pretty hot.

I don't have any ES/SD data to post because I haven't gotten any yet - just one round per load so far, except for two of the starting load.

So anyway, really the only place I'm confused by anything you've said is what you think the ladder test shows, and how to use the data from it. It seems to me now that you're saying more to just pick a load with MV in the desired performance range and start testing around it with 5-shot strings. If that's the case, are we just ignoring the ladder test? That's what I'm not clear on.

I'm also not sure what you meant by you can only see "two rounds in the paper with the target picture." I only fired ONE round of each load, except for the starting load since I needed a sighter/fouler.

So, after all that, what do you say to me doing the following:
I'll do 5-round strings at:

13) 92.5
14) 93.0
15) 93.5
16) 94.0

Then, look at the numbers and see what looks promising, then maybe zero in on what looks promising and possibly divide increments further. I can see maybe going to a 0.3 increment to fine tune, and I may be wrong but I'm going to be real surprised to see any significant changes with 0.1 increments on charges this big. That would be equivalent percentage-wise to 0.05 gr. increments on a .308, and that's a little more "fine" than I'd normally get.

Once again - man, I sure appreciate your taking the time to share your thoughts.

 

[Macmathews]

Re: Please Give Opinion On This Ladder Test (Pics)

Good discussion
And great advice from Lawnmower

Kyle

 

[LawnMM]

Re: Please Give Opinion On This Ladder Test (Pics)

I think I understand where we're disagreeing now. I suppose it depends on how much weight you want to give this ladder test in your decision for where to do your load development.

My issue with the ladder test method is similar to the whole 'shoot for group size' approach. Its not flawed, per se, but the people advocating it are some very high skill set level people that shoot probably tens of thousands of rounds per year. Their fundamentals are nailed down so well that they have a high level of consistency in their shooting and can draw some meaningful conclusions from how rounds impact a target at distance.

The problem is, we don't all have that high level skillset. Is the vertical change at 300 yards the ammo? Or did I shoulder the rifle a bit? Did wind blow crap in my face as I broke the shot? Have I not eaten that morning and my hands aren't as steady? Do I have a headache? See what I mean? I'm not critiquing your shooting, I don't know what your ability level is and it doesn't really matter. I'm just trying to help you put the weight of your decision making where it makes most sense. I have a hard time assigning a lot of value to where a single shot landed. Try to shoot yourself a .5" group or better at 100 yards with five rounds and you'll probably see the occasional group with one shot high and off to one side. Imagine if that was the shot you gave all the meaning to.

As far as shots with similar MV, shots 6-8 are 20fps apart, 10-12 as well, then 15-17. You WANT to be around 2700fps, so I think that's where you should start trying to narrow things down. Just because you CAN find a node higher, or the shots group a little closer in MV doesn't mean you HAVE to start there. If that makes sense.

I think doing five shot strings where you suggested is a good starting point. Then post back a photo of the groups each string produces, and the AV/SD/ES numbers for each string. Set up different points of aim for each group, but use the same one for all five shots of each group. Rifle doesn't have to be zeroed for this, just hold the cross hairs in the same place.

What kind of scale are you using?

If you can get into single digit SDs with .2gr or .3gr changes to your loads that's great, just don't be shocked if you have to tweak them pretty fine to achieve the end goal. A little bit goes a long way in the race to a single digit SD.

On shots 13-18 it looks like a second hole immediately to the side, was that a dot you drew for point of aim?

Rich

 

[vh20]

Re: Please Give Opinion On This Ladder Test (Pics)

Ha! Now we're rolling! You asked some excellent questions...

The "second hole" you are seeing is a Sharpie mark. It isn't the aim point - that was the same for EVERY shot - which was the center diamond bullseye on the white paper, which isn't even visible in the pic (it's up higher). I didn't zero the rifle - I just made sure it was on the brown paper for the lowest load, and anticipated the following shots would climb, and they did. I numbered each shot with a very small number written with a ballpoint pen. The numbers were too small to read in a photo, so I marked through them with a Sharpie and made them larger so you can read them. The second "hole" you're seeing is where I marked out the pen-written number. It wasn't really necessary to do that on the brown paper, but it looked a little jumbled on the white paper with two of the same number written by each hole, so I marked the original out.

My scale is an RCBS 5-10 scale I've had for 30 yrs. I calibrated it with check weights at 85.0 before I started, and checked it again @ 90.0 as my loads progressed upwards from 90.0 to 95.0.

I'll shoot the plan we discussed, and report back. It will be a few days before I can shoot due to weather coming in, but there may be a window on Sunday.

Thanks so much, Rich

Jim