How much spread between test loads?

[D.B. Cooper]

Something just hit me like a ton of bricks.

I'm looking at my load data book, and it says to use starting weight of 43.8 grains with a maximum charge weight of 48.6 grains. I've been loading 10 rounds each at every 0.1 grain increment. That's 48 different loads or 480 projectiles!!!

I shot my first 50 rounds yesterday (10 ea from 43.8 - 44.2 grains) and was throughly unimpressed. Very little difference in group size, and all between 1.75 and 2 moa. (One 5 shot string came in under 1 moa, but the 2nd 5 shot string of the same load was over 1 moa.)

So here is my question: how much spread should I put between my test loads? Should I be loading every .01 grain increment, or should I go in half-grain increments, or full grain?

I feel like I basically just wasted a 50-round box of projectiles ($35) and continuing down the path I'm on is financially unsustainable and will incredibly time consuming.

 

[Demi-human]

I do one percent increments. For a target rifle. So, four or five tenths of a grain for the case in question. Sometimes I use the list of charge wieghts by velocity, in the Hornady manual, more so with pistols.

At least you got to practice with your rifle, not a total waste.

 

[D.B. Cooper]

At least you got to practice with your rifle, not a total waste.

True.

 

[Walkalong]

No reason at all to start off doing .1 increments in rifle calibers averaging 45 grains of powder. .5 is more like it, and tweak after you find a couple of charge weights that show promise.

 

[Demi-human]

Yes, I only do tenths after I have found something close.

For instance. A TwoTwenty Three with this or that bullet is maximum load at thirty grains of powder. I will take steps of three tenths. I will only make three each. From ten percent of maximum or the starting load given. Shot next to each other, one will 'best'.
I will then take tenths of a grain above and below it. Five tenths each way, with five rounds of each, as now I am closer to an accurate load and so shooting them is more fun, but three could still work. One of these is the chosen one.

Of course you don't have to go that far, and could go much farther still. Just depends on what you want. I make ten of each sometimes, too!

 

[frankmako]

when i work up loads i don't work small numbers. (this is a example for the numbers for the rest of the post) say the starting load is 35.0. i will do some at 35.0, then 35.5, then 40.0, then 40.5 and so on to i get to max. this way i get chronograph reading on the speed and watch for pressure signs. most of the times there is not much different between 30.0 and 35.5 loads on the fps. but you can see a different between 30.0 and 40.0 loads. working small numbers is just waisting my time.

 

[FROGO207]

I load 3 at min, 3 at 1/4, 3 at 1/2, 3 at 3/4, 3 at max. Then look at the results on paper/speed and fine tune from there. Using the factory max speed as my top limit.

 

[Chuck R.]

I use the OCW method and created spreadsheet that does the math for me and spits out the test charge weights after I add in 3 max charges from different sources:

OCW:

3. Consult at least three load data sources for maximum charge weight for the powder you've selected. Powder manufacturers are the most reliable source. You must then decide on what your maximum charge will be. (My formula averages the 3 max charges for a stating point)

4. Back away from the maximum charge by 7 to 10 percent, and load one test round with this charge. Add 2% to the charge weight, and load another cartridge with that charge. Load a third test cartridge with the next 2% graduation. You will use these three cartridges for sighters, and more importantly to determine pressure tolerance in your individual rifle.

5. Add another 2% or so to the charge level used in cartridge #3 of step 4, and load three rounds with this charge weight. Add .7% to 1% to this charge (I went with .7% for my calculations), and load three more. Add that same graduation again, and load three more. Continue adding the chosen graduation until you have moved ONE increment above your chosen maximum powder charge.

On a 45 grain round the increments are usually .3-.4 grains per.

http://optimalchargeweight.embarqspace.com/ocw-instructions/4529817134

 

[bikemutt]

0.3 grains is what I use for a starting spread. I find it helpful to chrony what I'm shooting to see how what's happening in the field aligns with the book.

 

[Slamfire]

When I was doing load development for my 30-30 and 270 Win, I would pick a mid range charge and work up a grain at a time. And I often shot five shot groups just to get velocities. This was particular important with the 30-30 as the Marlin 336 I have, one grain differences in charges resulted in 2 MOA differences in impact!, maybe more! That lever action is about as rigid as a trampoline. I was also trying to hit a specific target velocity, for the 30-30 with a 170 grain bullet, I wanted an average velocity of 2150 fps. So, once I had my velocity spread with five round groups, I tested ten round groups at 0.5 grain increments, trying to dial it in.

I have 270 Win targets where the five round group showed great promise, but the 20 round group was hardly stellar. I will say, with a hand held rifle, I cannot imagine seeing anything with 0.1 grain increments. I have lots of chronograph data, and there is a lot of overlap in velocities with just 1 grain increments. Shoot over a chronograph and look at the high and low velocities. The averages will be different, but the velocity variation will have a lot of overlap. We have been programmed to think that a book value of 3000 fps means every shot is 3000 fps. That is not so. When the extreme spreads are 100 fps, that means groups that average 2900 fps, are going to have a lot of overlap with groups that average 3000 fps.

 

[Blue68f100]

I generally go in 1% steps, so in your case 0.4-0.5gr steps, 3 shots. I shoot 3 shots when doing my initial scan. Once I find a area where the velocity levels off I do smaller steps around these areas to see how big the node is and if what I saw was repeatable. You have to keep up with the environment in which you shoot. Particularly if you using a powder that is temp sensitive.

Also allow plenty of time for your barrel to cool. Shoot rotating orders to keep the fouling as even as you can.

 

[Bat Rastard]

With something new, I will start at min, and load to max in 6 equal increments, 5 rounds of each. Take it to the range and start with the low ones. If they were to get scary, I would stop. From there, if anything looked promising I load in smaller increments around the ones that showed potential.

 

[Dibbs]

I start with the lowest recommendation, but work thru to highest quicker. I try to find a general
area, then focus on that weight, with 5 half a grain light and heavy, till the groups tighten up,
and it feels right.
In your example I'd load 5 at 43.8, then 5 at 45.8, then 5 at 47.8. From there, I would start working in the direction of what was shooting out of my gun best. IME, it's usually at the lower end of the scale, like
maybe 44.1 or 44.2

 

[Varminterror]

You REALLY have to have expensive gear to be able to accurately measure loads precisely enough to throw 0.1grn increments. Standard reloading gear won’t cut it.

As others have said, 0.3grn increments is plenty refined for a middle of the road cartridge, but in many cartridges, that just doesn’t apply. Some guys use 5% increments, some use 10%, some do percentages of the data gap in the manual. Personally, I don’t play rule of thumb games. I look at the book and the speeds reported for each powder, if my bullet exactly matches the book (not some generic 150grn pill looking at Hornady 150 SST data, for example), and if the gap from start to max is large, and if a starting load is too slow, and I know I will never run a load that slow, I don’t bother with starting at the starting load.

I’ll preface my method by saying I have not found a qualitative difference between the OCW and Ladder methods, it’s just a difference in the small details of execution. I back both up with a velocity curve. Honestly, I could give up on the ladder or OCW test, and simply use the velocity curve. It has never lied about any node I have found yet, and it gets there with much fewer roundcount. In the node, I usually have small clusters, or at worst, horizontal strings, and a little seating depth tuning clears that up. So I strap on the chrony, shoot 600yrds, and come out with a workable next step. Repeat with smaller increments, tune seating depth if needed, done - go shoot half MOA ammo...

 

[jmorris]

You REALLY have to have expensive gear to be able to accurately measure loads precisely enough to throw 0.1grn increments. Standard reloading gear won’t cut it.

I have never found it difficult to get .1 gn precision using normal scales. With the right powders even volume measures can throw within a tenth, no problem.

To be able to tell the accuracy difference between loads a tenth of a grain different, is another matter though.

 

[someguy2800]

I never really thought about it but I guess I do usually do about 1% increments to start. Typically like .5 grain intervals with 308 or 30-06 sized case and .2 or .3 grain intervals with a 223 sized case. I also usually start about 5% under max. If I get good results I'll usually leave well enough alone, if not I'll probably just try a different bullet or powder.

I've personally found over the years that the bullet selection and powder type are way more important than specific charge weight. After chasing the accuracy rabbit down the hole for years I honestly just don't care enough anymore to load hundreds of test loads trying to find the goldilocks load. I typically try 3 or 4 different bullets and a couple powders with a mid range load and usually something reasonably good presents itself. I pick the one I like the best from that and load 4 or 5 charge weights. I just don't care to spend all day loading anymore, I don't have the time.

 

[Demi-human]

...
and if the gap from start to max is large, and if a starting load is too slow, and I know I will never run a load that slow, I don’t bother with starting at the starting load...

Sometimes I start in the middle, too. But I don't tell anyone that.

Oh... Dang.

Oops!


In the beginning, beginners should begin at the start. (I have to say that, legal stuff.)

Advanced classes are next week.

 

[Varminterror]

I have never found it difficult to get .1 gn precision using normal scales. With the right powders even volume measures can throw within a tenth, no problem.

I guess it depends what you call "normal." Normal reloading scales are all rated to be +/-0.1grn, as such an interval between charges MUST be larger than 0.2grn to ensure it's actually different. For example - Cabela's doesn't sell a single powder scale which is accurate to less than +/-0.1grn. Brownell's only sells TWO models more precise than +/-0.1grn. So even though that screen might read 42.0grn, it might really be holding 41.9 or 42.1, and you'll never know the difference, because the scale can't tell the difference either. So if you throw two charges, a 41.9 and a 42.1, both might read as 42.0 - or if a guy is running 0.1grn increments like the OP, he might have the EXACT SAME CHARGE WEIGHT display as his 41.9, 42.0, and 42.1 - a guy might even have charge weights change places, where a 42.1 reads a 42.0 and a 42.0 reads a 42.1 so the resulting trend on the datasheet is absolutely meaningless.

Most guys CLAIM they throw or dispense to 0.1grn because their scale says they are, but when you work with a real analytical balance (with precision down to +/-0.015grn), you can see the fallacy in most guys favorite toy. Even balance beam powder "scales" (really a balance, not a scale) typically have too much internal friction to deliver better than +/-0.1grn. I run a Mettler Toledo MS-603 (they run around $3,500-5,500 depending on the feature set you order), accurate down to +/-0.015grn and have checked the precision of many dispensers and scales over the years, including three Lee Safety Powder scales, two RCBS 505's and a 1010, and a Lyman Pro500 all had enough internal friction they weren't more precise than +/-0.1grn. Also have done Uniflows, Lee PPM, AutoDrum, and Autodisk, Hornady BR's, and Lyman dispensers, none were precise enough to be +/-0.05grn (aka, precise enough to deliver no more than 0.1grn variation).

The Gempro 250 is an example of one scale which has been around in the reloading world for a long time which does read down to +/-0.015grn. Unless guys are running a Gempro or a very expensive balance, if they tell you they load to 0.1grn increments, they're lying to you AND to themselves.

 

[Walkalong]

The Gempro 250 is an example of one scale which has been around in the reloading world for a long time which does read down to +/-0.015grn

And when you are used to using balance beams for years (decades) it takes some adjustment mentally switching over to the GemPro, which I did a year or two ago. I note what scale I use in my load book (Well, Excel file). At first the GemPro makes it seem like the spread is bigger, but you have to keep reminding yourself you are reading to .01 now instead of .1.

 

[ArchAngelCD]

I use a spread of between .5gr and 1.0gr initially depending in how wide the charge range is.

IMO a graduation of only .1gr in a 5gr spread will not tell you much unless you are using a rest to remove the human factor. Most shooters are not good enough to shoot .1gr charge changes and see real results.

It's really not all that complicated and all these "systems" on the Internet are a bit of overkill too IMO. I hear a little information is dangerous. So much is written about precision match shooting with fractions off the lands and run out of .0001" it gets confusing for the common reloaded with a hunting rifle. I don't pay attention to a lot of it because today's rifles are so accurate from the factory so if I do a consistent job of loading my ammo game will fall cleanly.

 

[jmorris]

and have checked the precision of many dispensers and scales over the years, including three Lee Safety Powder scales, two RCBS 505's and a 1010, and a Lyman Pro500 all had enough internal friction they weren't more precise than +/-0.1grn.

I have played with 505’s and 10-10’s with photo electric switches and they can detect the addition of a single kernel of powder.

That’s well inside .1gn.

 

[Archie]

My test loading is usually: 2 rounds per charge weight. Not ten to start. Divide up the spread from minimum to maximum and see how that divides into four or five test groups. Usually for basic testing I load about a grain apart. Once I determine which level gives me the most consistent results and best accuracy, I'll load three each and vary the second series by .5 grains each. Final testing is done in groups of ten. All sets of tests are chronographed and the 'finalists' tested for groups at one hundred yards. Later I will probably check them at two hundred yards to see if the zeroing process is holding and the 'drop' is what I think it should be.

This may seem a bit over reaching in the initial stages, but I shoot minimal loads first and check for surprises in the velocities and indications of over pressure. So far, I have all my fingers.

Super consistent powder weights are typically over rated unless the rifle has been worked over serious prior to developing the load.

 

[Chuck R.]

I have played with 505’s and 10-10’s with photo electric switches and they can detect the addition of a single kernel of powder.

That’s well inside .1gn.

Same here, all I did was "tune" my 10-10 and add a document camera to a laptop and I can easily see the delta for a single kernel of H4831 Short Cut. Snapshot from the CAM:

 

[jmorris]

Same here, all I did was "tune" my 10-10 and add a document camera to a laptop and I can easily see the delta for a single kernel of H4831 Short Cut. Snapshot from the CAM:

View attachment 818864

There is a fellow named Scott Parker who is well acclaimed in some circles for “tuning” them, I always wondered what he did to them.

Mine are old ones that are as RCBS shipped them.

 

[Demi-human]

I always wondered what he did to them.

A detailed cleaning, truing of the pivot points, sharpening of the agate stones and truing them with the pivots, ensuring that the magnets are glued in their places properly. All the things that are cut out of the last step of mass manufacture.

I had thoughts of getting one. A Gempro is easier for me though, my space is tight, it just takes less room.