Smallest powder incriment in ladder building.

conan32120

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Realizing that caliber makes a huge difference I'm curious what your smallest powder increments change is in a fine tuning ladder. I can see how .1 grain change can a difference in .223 but probably not in a .458. In my .308 loads my first ladder is .5 grain rungs and I've been fine tuning at .2gr and sometimes see no difference. So let me ask what caliber and what powder weight do you build your rungs?
 
Realizing that caliber makes a huge difference I'm curious what your smallest powder increments change is in a fine tuning ladder. I can see how .1 grain change can a difference in .223 but probably not in a .458. In my .308 loads my first ladder is .5 grain rungs and I've been fine tuning at .2gr and sometimes see no difference. So let me ask what caliber and what powder weight do you build your rungs?
Are you talking about precision competition with rifles only?
If so, I have no opinion. But for the full universe of handloading I would have to say .25ACP and .32S&W are the least forgiving of variation. I load top-break .32’s with carefully weighed charges, 0.1gr steps, zero tolerance.
 
I vary it by case capacity using a spreadsheet based on the OCW method. For instance .223 might be .3 while a big boomer is .5.

.223:

Test Loads: 3 or 4 Rounds Each
Charge 1
26.8​
Charge 2
27.0​
Charge 3
27.2​
Charge 4
27.3​
Charge 5
27.5​

300WM:

Test Loads: 3 or 4 Rounds Each
Charge 1
75.3​
Charge 2
75.9​
Charge 3
76.4​
Charge 4
76.9​
Charge 5
77.5​
 
I like round numbers, so most of my loads are either in whole grains, or .5grn increments. 8.5grn Unique, 47.5grn IMR4895, 24grn IMR4227, for example. If I am hunting for a accuracy node, or I'm creeping up on max data, I work in .3grn increments.
 
For rifles, .3 grains is the smallest increment I work in. I can't remember what I did for pistols the last time I developed a new pistol load, but I probably worked in .1 or .2 grain increments. My scales' accuracy are all listed to within +/- .1 grains, so I don't see much of a point working in less than .3 grain increments most of the time (there are always exceptions . . .). But I don't load cases holding less than 20 grains of powder most of the time either.
 
I find .2 is enough change to observe differences in my scales resolution. I may map a node loading .2 grain steps. Rifle is mostly .3 and pistol .2
 
0.2 grains usually. Then when I find two adjacent loads shooting similar velocities and to the same spot, I split the difference for my next loads. So usually my loads are "odd" numbers; 21.3 grains for example, instead of 21.2 or 21.4
 
Don't remember where I first heard of this, but the logic of it seems to hold up. For rifles, It seems there are two tuning dials you can turn. One is powder charge. The other is seating depth. So along the lines of chicken / egg and which came first debate, I've settled on powder charge comes first, Then seating depth if you need to go that far, with caveat that bullet seating depth to start is either something like 30 thousands off the lands, or to the COAL listed in the load.......or to SAMMI max if it will chamber. Either way, it is out far enough if you want to adjust it, you adjust it in 3 thousands intervals (seated deeper).

But as for powder charge, the increment that seems to hold up well is 1% of max charge in load data. So if max load is 50 grains, 1% is .5 grains. I have found i like to end at an accurate node close to full case capacity / max load, so I start at Max, then back down 6 increments from that. In above example, that would leave me at intervals of 47.5, 48.0, 48.5, 49, 49.5 and 50. That usually leaves me about halfway between min and max. Top half. Four rounds each. Lacking signs of pressure, best group that gets me close to factory ammo velocity wins. Then if you want to try to tune it more, same thing with seating depth. 4 rounds each, seated 3 thousands deeper, looking for an accuracy node inside what ought to be an already accurate load. Since I'm loading hunting ammo for hunting rifles, 1 MOA or better is good enough for my use and I can usually do that with no need to tinker with seating depth.

Pistols.......in my case 9mm.......COL to book or longer (seated further out), then increments of .2 grains. I'm looking at a combination of velocity and an easy shooting feel that loads and cycles the gun when fired. If I keep shooting enough of these, hope to someday get to the point where accuracy matters too.
 
With smallish cases such as 6 br ( 30 ish gr) I start with .2 gr increments, with a larger case like 308 win ( 44 ish gr ) start at .3 gr. I could go to .5 in a large magnum. From there I can load in the middle of a node or refine to smaller increments. Nodes tend to repeat about 3% of case capacity, but not always..
 
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I’m just punching holes in paper, but my goal with every round is accuracy. In pistols I go .3 to find an accurate node then refine that by .1 until I hit the sweet spot. In 223 I start with .5 and work down to .05. It’s the only rifle round I’m still loading and I have a few different rifles in 223/556. Each one gets its own load, as do my 6 9mm’s.
 
I’m just punching holes in paper, but my goal with every round is accuracy. In pistols I go .3 to find an accurate node then refine that by .1 until I hit the sweet spot. In 223 I start with .5 and work down to .05. It’s the only rifle round I’m still loading and I have a few different rifles in 223/556. Each one gets its own load, as do my 6 9mm’s.
Very good. That's your hobby actively. Mine used to be volume of usable ammo.
 
I use the 1% of charge rule most of the time. On rifles it's not a real big problem but if you have a narrow node you may jump over it. I generally go back and fill in the gaps if something warrants it. For small capacity handgun I step in 0.1gr. In some calibers like 380 acp that is too much depending on powder used. Some of the smaller cal only have 0.3gr spread from low to max. For those I shoot for the middle unless I'm going to weight every charge.
 
Check this out:



There are some more things on the same channel that might help answer some of the questions that come up. To address the question in the OP. "it depends" on what your goal is. "Finding the best possible load" is not a practical goal. With all the variables involved, you would have to plan to shoot a barrel out before finding it. What is a more sensible goal is to find a load that avoids more obvious problems. The kind of problems you need to avoid depend on what kind of shooting you are doing. The requirements for PRS are different than F-Class. The requirements for a hunting rifle or a home defense rifle are different again. I used to resent the idea that I couldn't develop the "best" load for my hunting rifle using the same methods F-Class shooters use, until I understood why an attempt would be a colossal waste of components and barrel life, and I wouldn't get the result I wanted because of statistical noise.

I shoot ladders to get ball-park velocity and find maximum pressure. I'll shoot up to book max as long as I don't see pressure signs before then. The increment? The idea of shooting a smaller increment for smaller cases or an increment proportional to case size makes sense. On the other hand, the meaningful data doesn't require the smallest increment.

You mentioned "tuning ladders" which I believe you mean to be about looking for velocity nodes. I'm skeptical. First of all, I doubt a velocity node can be reliably found with one shot. Five shots at each increment and you might see something you could use, but also might not.
 
Honestly this would be much more insightful if it was a two part question, what size are your testing increments and what is the accuracy/resolution of your scale. Some people have really good scales, and some probably are chasing resolutions beyond their scales capasity....
I use an RCBS M500 scale. I don't often trickle charges, but when I do it will move with anywhere from 1-3 kernals of powder, depending on which powder I'm using. The larger sticks will usually move with just a single kernal. Maybe I got a good one, who knows.

I have check weights that I use from time to time to verify the accuracy of the scale.

Charge weight increments really depends. Like others have said, what is the min/max range? 0.5 grain range gets 0.1 grain increments. For rifle it's usually 0.2 or 0.3, again depending on min/max range.

chris
 
For ladders.... I go a different route.

1) Subtract the Starting Load from the Max Load, and then divide that Load Range by 5 (or 6 if it works out better).

2) For handguns that usually works out to ~0.2gr. For rifle that's maybe 0.4 or 0.5gr, but it's OK. Then load at least 6 each in matching brass.

3) If the targets reveal 2 adjacent loads with good looking groups, I usually go back and load in 0.1gr increments between those two. I do this to find THE best load. I take the time to do this because I know there will always be tiny variations in powder, OAL, brass internal volume, etc due to loading on a progressive. The results of this are analogous to aiming at the 10 ring and peppering the target with 9's, versus aiming at the 6 ring and peppering the target with hits on every ring between 9 and 3.

[And of course, the other reason I do this is because my boys have hit their mid-30's and have turned into good shots themselves. I need every advantage I can find. Can't have those young up-starts thinking that the "old man" is slipping. :cool: ]
 
Shoot 50 more and you might find you're looking at noise. 1 or 2 or 5 shot-per-charge-mass ladders are statistically insignificant. You can see whatever you want to see. I'm not saying they won't ever show you the answer, but that you can believe they're showing something meaningful when they are not.
 
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