Multiply by 3, then divide by 4?

[Metal god]

If you look at any manual you will see the charge weights correlate to a specific numbered velocity in 100fps increments . It's why you see 21.2gr rather then 21.0 . Why bother with that when loading for rifle loads . If it says 21.2 , I'll start at 21.5 then 22 , 22.5 , 23 etc . If there is a huge amount of grains between min & max . I'll start at or very close to minimum and load two rounds working up in whole grain increments loading two of each for about 1/3 the load ladder then 3rds in 1gr or .5gr increments for the next 1/3 then 5rds in .5gr increments for the final 1/3 of the ladder .

The first third is only for checking pressure and is why I only load two rounds at each charge . The second third is with 3rds also really only keeping an eye on pressure but looking for a group just in case I shoot something real tight I can go back to it . The last third is where I'm expecting the loads to shine and is why I start loading 5rds per charge .

I generally load in .5gr increments from around minimum . That usually is 5 to 8 different charges . I don't have my notes in front of me be I think RL-15 and Hornady 168gr BTHP had quite a large gap between min and max loads . If I recall , if I would have done the .5gr increments I would have had to load 13 or 14 different loads to hit all charges from min to max . That to me just seems to be a waist of components . I did those test with ten different loads saving 14 bullets , primers and powder .

Hey found a pic of that very load development .

 

[BBarn]

Never heard of the times 3 divide by 4 practice referenced to establish a starting load. Nor would I practice it or recommend it.

The practice of starting about 10% below the max charge has been a common practice in many loading manuals for many decades. There have been some instances in the past where recommended starting loads with certain powders were 6% below maximum. And there have also been a few loads that were to be used exactly as published (no reduction in charge weight).

Some manuals show loads that go significantly below a 10% reduction. That indicates to me that with that particular combination, you can safely reduce to those levels if it provides the velocity you are seeking.

I guess I’m simply suggesting that if one wishes to work up to a maximum or near maximum load, the proper place to begin is the recommended starting point specified in the loading manual (usually a 10% reduction, sometimes a lesser reduction).

Encountering high pressure signs well below the maximum powder charges listed in the manual (as I have) gives one a better appreciation for the published starting point recommendations. I know of no compelling reason to begin anywhere other than starting point recommended in the loading manuals.

 

[849ACSO]

What happens when your most accurate load is in the bottom 4th of the load range?

I don't want to sacrifice accuracy for speed.

EDIT - I changed the words accuracy and speed - I had them reversed and TOTALLY ruined the initial thought.............

 

[44 AMP]

What happens when your most accurate load is in the bottom 4th of the load range?

I don't want to sacrifice speed for accuracy.

The standard reply is that speed is irrelevant if you don't hit your target.

The practical answer is that a handful of fps is also essentially irrelevant.

Sure, the slower bullet drops more, but does "more" matter that much?? I say this, because if you know what your load's drop at a given range is, then how many inches it is doesn't matter.

Take that .223 slug, 55gr BC .23 (in this example). MV of 3200fps it drops about 12" at 300yds.

Same slug, MV 3000fps, it drops about 16" at 300yds. Some will look at this and say "that's 25% more for the slower round!!"
Others know that if you can compensate for 12" of drop, you can just as easily do it for 16" (other bullets and speeds will of course have different numbers, but the point is still valid with any numbers, if you can do for one, you can do for either just as well)

Most of the loading data I see is about a 200fps spread, often less, between starting load and max load.

SO, if your best accuracy load is in the lower end of the velocity range, I don't think the difference in speed matters as much as how much difference there is between your best, and worst accuracy. If you need minute of prairie dog, and a min load gets you there, while the max load gives you minute of moose, the extra powder is wasted. And the opposite is sometimes true.

Usually max loads don't group as well as slightly lesser ones, but some guns are the exception to that general rule.

You just have to work with your own stuff and see what it does.

As to the formula, never heard of it, anywhere other than here, today, and I've been handloading since the early 70s.

It did make me wonder, since there is such a wide difference in powders and cartridges, how anything like that could work (and work safely) will all possible combinations, but then I realized that since ALL you are doing with it is using it to pick a random starting point within safe published data, that it really couldn't do much harm.

Seems like you could throw darts at a list of possible starting points and do as well, though.

 

[849ACSO]

SO, if your best accuracy load is in the lower end of the velocity range, I don't think the difference in speed matters as much as how much difference there is between your best, and worst accuracy

That was exactly my point. I work my loads from minimum up, as I don't want to miss my accuracy window by totally discounting the loads in the bottom 4th of the load range, as others above have said they do.

Seems counterproductive to be less accurate, but do it "faster"...................

 

[Unclenick]

Rangerrich99,

The problem with that formula is the premise, which is that the professional powder and bullet makers don't know what they are doing when they establish a starting load for your workups. While starting in the middle works out most of the time, I have twice encountered starting loads that were already at the maximum for the guns they were tested in. That's unusual. It's more usual that my gun can handle a hotter load than the published maximum. But the starting load being pretty hot already is just not something that never happens. So you need to allow for it.

You can prove the above to yourself simply by reading published load data. Every once in awhile you find a combination for which one manual's maximum is at or below another manual's starting load. I'm sure they were both right for the gun and components and the exact burning rate of the particular lot powder they used to developed their loads with. So, if I own the gun the company with the high range tested in, I'm good to go with the lower load data. But if I own the gun the low charge range was developed with, I would be foolish to use anything above the high charge range company's starting load data in it. And even that may seem pretty hot for it.

Here's how you save money on test ammunition: most load data has starting loads 10% below listed maximum loads. It's an old rule of thumb that generally works. It will reduce pressure 20-30% or so, depending on the chamber and the powder and bullet. What is safe is to increment loads by 2% of the maximum charge, which does not raise pressure more than about 5%. Make just one load at the starting load, and five more, each at a 2% increment until you reach the maximum. It's just 6 rounds. Go to the range and shoot them from bottom to top, watching for pressure signs. If you don't get any, you should be good to go with the whole load range. If you get one along the way, stop. Backup, and then work more slowly or shoot enough to test for a sweet spot load in between.

One reason for owning a Lee Hand Tool is to charge cases at home, put corks in, then have the Lee tool with your seating die in it. That lets you seat each bullet just before firing. It saves you having to put bullets over charges that you've figured out are going to be too high.

 

[wogpotter]

I have twice encountered starting loads that were already at the maximum for the guns they were tested in.

That is exactly why I split the difference between the lowest HIGH & the highest LOW.

 

[Rangerrich99]

What happens when your most accurate load is in the bottom 4th of the load range?

I don't want to sacrifice speed for accuracy.

Bearing in mind that I've only used this formula about 20 times, I've never had the most accurate loads come in below the formula's abbreviated range. In fact, my most accurate loads seem to come within 0.3 to 0.9 grains of max. So far, anyway.

Several of you posted your own methods of producing test loads, and that's been very helpful. More ways to reduce the total amount of material used are always welcomed around here.

@44AMP:

It did make me wonder, since there is such a wide difference in powders and cartridges, how anything like that could work (and work safely) will all possible combinations, but then I realized that since ALL you are doing with it is using it to pick a random starting point within safe published data, that it really couldn't do much harm.

I'll admit that the first I considered using it, I had some concerns about exactly the same things. Once it became apparent to me that the formula was essentially just eliminating the bottom quarter or so of the original range I was less worried about it.

Based on the replies I've gotten (thanks again guys), I'm thinking the formula is really just a way to shorten up the range a bit, without entirely sacrificing the lower end of a given range; a way to reduce the total number of test loads. Some of you seem to have easier ways to go about it though, and I'll probably try out a couple.

Going back to my original question, it seems that no one here has heard of this mathematical gimmick or anything like it. Also, it seems that there really isn't any real risk in using it or something like it. At least according to everyone's posts so far.

Thanks again and keep 'em comin'.

@Unclenick,:

While starting in the middle works out most of the time, I have twice encountered starting loads that were already at the maximum for the guns they were tested in.

That's food for thought. May I ask for which two cartridges did that happen? Just so I can be aware if I decide to get a gun in those calibers.

 

[Jim Watson]

Sounds like a lot of head scratching for little return.
If you want to start with a 7.5% reduction instead of 10%, just multiply the maximum by .925.

Speer lists - or listed, I don't have a real recent manual from them - three loads per bullet weight. The highest is presumably the pressure maximum, the lowest is -10%, the middle is -5%. I NEVER had any trouble loading the middle powder charge. I seldom found any reason to increase from it for ordinary military and hunting rifle loads, either.

 

[Metal god]

What happens when your most accurate load is in the bottom 4th of the load range?

I don't want to sacrifice accuracy for speed.

I think in general that's a good way to approach this . In fact when loading match target ammo I almost always take accuracy over velocity . To the point if I find a load that shoots "really" well I'll stop looking for a better load at the higher charges . Example : 38.5gr N540 , 190gr SMK , WLR primer , PPU cases shoots/shot lights out in every rifle I ever tried it in . (9 to date) . There were other charges that had potential but I felt there was no need to look any further then sub moa out to 300yds with very little effort on my part .

That being said I also have given up a little accuracy to gain a little more terminal velocity for hunting loads . When I say giving up accuracy . I'm talking 1 moa to 1.3moa . Nothing that will be noticed with accuracy in field conditions but does pack a little more punch .

I also have tried pushing the velocity to accuracy ratio when trying to load long range target loads .

My point is that I do try to stick with accuracy over velocity but there are a few exceptions to that rule . YMMV

 

[Unclenick]

Rangerrich99,

It's because all you are doing is changing the typical starting load from -10% to -7.5% to create your own risk taker's starting load. The problem is that Hodgdon and others have some starting loads already only about -7.5%. Do you then also split that down further? I just don't think there's a hard rule you can apply here that will always work.


Woggpotter,

Sounds like you're still starting in the middle range somewhere. I don't. I chicken down to the smallest starting load I identify. Here's why: About 35 years ago I was shooting a lightweight .44 Special Charter Bulldog using the smallest charge weight of 2400 then listed by Hornady for their 240 grain JHP bullet in that chambering. That load made my palm sting and case extraction was slightly sticky. Darn glad I didn't go even a fraction above that lowest load in that gun.

So I didn't think about the subject much again until many years later there was a fellow, I think on this board, who was using a .243 Win load from a Speer manual, and he was just past the middle load and his Handi-Rifle action was popping open after every shot, the primer was very flat, and his velocity was a couple hundred fps faster than it should have been. He knew about the Handi-Rifle latch debris issue and was keeping it clean. So it just seemed to be a load too hot for that action.

He contacted Speer, and they stood behind their test data. Clearly not helping in this case. And hey, for all I know his scale was off or something. But it caused me to remember that only God is perfect. Human beings make mistakes. Could be the loader. Could be the guy authoring the load manual or the technician operating the pressure gun, but mistakes do happen. Running at the bottom starting pressure spares you experiencing some of these errors.

It also dawned on me, somewhere around that time, that the reason the term "starting load" has the word "starting" in it was not because that's where the list of loads starts. It's actually where the manual author expect the shooter start his load workup.

 

[44 AMP]

Quote:

While starting in the middle works out most of the time, I have twice encountered starting loads that were already at the maximum for the guns they were tested in.

That's food for thought. May I ask for which two cartridges did that happen? Just so I can be aware if I decide to get a gun in those calibers.

Here's the thing, Ranger, other than being nice to know, that information will do you no good, at all.

Because you don't have those guns, or that ammunition.

When it comes to all the published reloading data, it's like the Pirate says, "they aren't rules, more like goidlines, really..."

What I'm saying is that while the published data is accurate, it is only 100% reliable for the guns it was tested in. Your (and my) gun, and our particular combination of ammo components, no matter how closely we could try to match the test data gun and ammo, will NOT be 100% the same.

90%+ of guns and ammo, will have results similar results to the published data, A handful will match exactly, (but that is serendipity), and a small percentage will vary considerably.

IT's not dependent on what cartridge is it, or what make and model gun it is (directly some actions have different limitations, etc.,) it is a matter of the individual gun, and also how the different factors (tolerances, including ammo components) line up.

One gun I knew cratered primers with every factory load. Otherwise the function was flawless, and it was accurate, but it cratered primers, because that specific gun was "tighter" than usual (no it wasn't a firing pin/hole issue, we checked).

In a gun like that, the listed "starting load" might be your working MAX.

Also, as anyone who has played around with handloads a bit can tell you, there are SOME guns that will handle powder charges well above listed maximums without showing pressure signs.

The published loads are absolutely safe in the individual guns they used for testing. There is a very, very high probability that they will be safe in your gun, but not an absolute certainty, which is why the standing advice has always been start low and carefully work up.

You can ignore the bottom 1/4 (or whatever) of the listed data, and start in the middle somewhere, and go your whole life with no problems because of it, but be aware that you are playing the odds and sometimes, although rarely, the odds don't cover you.

you might, for instance, pick a middle of the list spot to start, and find out you almost can't open the bolt after firing. It is a very rare thing, but it can, and has happened. This is also why I cringe at the "veteran reloaders" who say they don't bother with all that stuff, they just start at the max loads, and "never had no trouble".

They're fine, SO FAR. They MAY get away with it for life. Or, their next gun might just bite them (damage, even failure) simply because they ASSUMED that everything has the same max limits. It doesn't.

 

[Rangerrich99]

@44AMP;

Of course, you're right. Again. i just didn't think it through before I typed my question. Curiosity killed that cat and all that.

And after reviewing the many replies to this thread, I've decided that, for safety's sake, I'm going to make at least a couple loads at the starting charge weights to check for excessive pressure signs from now on. I figure it's a really small price to pay in time and materials to prevent a possibly very dangerous mishap.

Especially since I've just begun to reload .30-06 and I've had some concerns about safety, considering the much higher charge weights involved.

I now plan on trying to use some of the reloading strategies some of you posted, and thank all of you for your input.

I still find it curious that two strangers (to each other) here in Phoenix knew of this math gimmick but no one on here had heard of it. Maybe it's a local thing? Ah well, guess I'll never know now . . .