Home Forums Reloading Big Game Rifles Weigh and Anneal

Well done!! If you have enough of them on the bench, you will end up with the "bell shaped curve."

Continual Process Improvement..that`s how I look at my handloading.

Of course! Thanks for pointing it out.

2 boxes of 264 win mag, Nosler brand brass. One box is 20 grains heavier than the other. Equates to about 1 grain of powder difference in velocity.

I have done the same for weighing cases for precision rifle loads. Once enough cases are on the table, they'll show a bell curve of some sort (often with a long tail to one side but not the other); I take the largest chunk of cases in the middle and discard the outliers. Of course that is only done after cleaning, trimming, etc.

Doing that has shown some surprising results in how much difference it makes to accuracy; sometimes the difference is quite a lot. It also shows which brands are pretty consistent and which are not, and those results can be surprising as well, with more expensive brass sometimes being less consistent.

I’d like to hear more about the weighing the powder charges. I probably won’t understand the math, but I’m interested in the effects.
I find with my powder measure that the charges can vary as much as .3 gr with the powders I use (H4350, Varget, H4831, RL 16). Right now I load for 6.5CM, 6Dasher and 22BR.

It's a never ending discussion about weighing charges and dropping them. Typically benchrest shooters measure only and it's difficult to argue with their results. I bought a Harrell measure and used it for a while but whether it was the compulsion for perfection or what, I went to weighing every charge. I truly didn't see much difference either way. There are arguments for both methods. For me, if I had a shot go out on an otherwise solid load, I just wanted to know it wasn't powder quantity. Years ago on this board, one poster used to say "Build it like you were building for NASA." That poster may still be here.

I am not a benchrest shooter.

I quit weighing every charge some time ago. I really don't think it is the biggest factor - seems like I've seen a list somewhere of biggest factors for accuracy. Sizing a straight, consistent piece of brass is where all the concentricity starts. My guess is that if a piece of brass weighs different from the mean, perhaps it is thicker on one side than the other and out of round.

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The math isn't very painful.

The basic concept is that variation does not simply add. If you're shooting 6" groups offhand at 50 yards with a perfect rifle, switching to one that does 2" groups at 50 yards (an SKS!!) will NOT make your groups 8". It will make them more like 6.3". If there is one large source of variation in the chain, it will almost completely determine the total variation. That is why fiddling with small sources of variation is pointless. You have to find the big sources if you want to make any progress.

One good measure of variation is standard deviation. The higher your standard deviation, the more spread out your data are (and the higher your "extreme spread" generally will be). Standard deviations add by the square root of the sum of the squares. It sounds forbidding, but it's really not so bad if you work through it step by step.

Take the case of the 5.56/223. In a small case like that, small changes in the powder charge are more important than they are in a large case like the 30-06. So this small cartridge is sort of an "acid test". The changes in larger cartridges will be less important.

With a stick powder like Varget, my powder measure throws charges with a standard deviation of .11 grains. In the 223, near normal loads, a grain of powder is about 100 FPS in MV. So a standard deviation of .11 grains in charge produces .11 x 100 = 11 FPS standard deviation in muzzle velocity.

It's not too hard to get the standard deviation of 5.56/223 handloads down into single digits, but commercial ammunition tends to run at about 30 FPS standard deviation of muzzle velocity.

So for purposes of illustration, assume that a handloader is making 5.56/223 ammunition with a standard deviation of 30 FPS in muzzle velocity. As part of the process, the handloader is using a lab grade scale, and is creating powder charges down to the last 1/10 of a granule of powder, essentially perfect loads.

OK... starting from perfectly measured loads, and a 30 FPS standard deviation in MV, what would be the effect of switching to my Lee Perfect Powder Measure that has a standard deviation of .11 grains?

First, we square the two standard deviations involved:

30^2 = 900

11^2 = 121

Now we add the two squared numbers: 900 + 121 = 1021.

Now we take the square root of the sum of the two squared numbers: square root 1021 = 31.95.

So going from a perfect measurement of powder to my $27 powder measure increases the standard deviation of muzzle velocity from 30 FPS to 31.95 FPS.

QED

I hope you're not sorry you asked!

Anal brass prep should pay dividends. Sorted once fired, reamed/turned, trimmed brass from 400 down to 100 closest in weight and halved group size with a Ruger 1V in 22-250. Anything that helps deliver a consistent product most certainly can't hurt.

I was right,,,,,it’s complicated

Thanks for the breakdown. Looks like this is a step I could probably skip and just drop charges from my powder measure. And a good excuse to get a new powder measure. I’ve had mine for 20 years and I have no idea how long the old guy I bought it from had it, but it was well used. Thanks again.

That wasn't complicated.

denton's explanation is a great example of getting too wrapped up in theory to see the reality. He claims that "for practically all applications" weighing charges doesn't matter, while attempting to prove it with a very limited set of information. NOPE. Sure, there are some examples where that is true, but that does not make it universally true, or even most of the time.

It's easy to find plenty of examples where weighing charges does show a significant difference on target. Take a 223 & Varget load that has an accuracy node about 0.3gr wide, which is fairly common. Now load that with a powder measure that varies +/- 0.4gr with Varget (meaning dropped charges span a range of 0.8gr), which is also fairly common. If you don't weigh those charges, you get a fair number that are way outside the accuracy node and the difference can be significant when shooting at extended ranges on small targets like ground squirrels. Good for denton if his powder measure is more consistent than that, but there's a big gap between saying it works for that one powder measure, and saying "practically all applications".

As to the weighing vs measuring argument - powder energy is a function of the mass of the powder, not the volume dispensed, and most powder measures dispense by volume. Dispensing without weighing can sometimes be as accurate, but weighing is never less accurate. If someone claims it is, their test was flawed or the sample size was too small.

Same goes for weighing cases. For example I've got a 357 Sig load, and a batch of brass with weights in two distinct groups. Velocity from the heavier group of brass is approximately 100 fps faster than the lighter group (about 1750 fps vs 1650 fps). That makes a noticeable difference, so I choose to sort that brass.

Often this stuff doesn't matter, but sometimes it does.

About the OP's annealing question - yes I anneal as needed. It can help accuracy by making neck tension more consistent, but even more than that it helps cases live longer without cracking in the neck or shoulder.

This is an oversimplification. Unless treated with a waterproof coating, modern smokeless powder is hygroscopic so its energy density and its mass density are both functions of its exposure to humidity. Its macroscopic volume, however, is not dependent on exposure to humidity.

Yes, but from the same batch, reloaded at the same time, their volume would still be uniform charge to charge. That would only vary the weight of the charge very slightly, especially in the lighter loads.

Wow. If your powder measure is really that bad, we ought to chip in and treat you to a new one that is at least mediocre.

With Varget, my Lee powder measure has a standard deviation of .11 grains, measured. So 95% of charges will fall between plus and minus .22 grains, and the math works out as shown.

As stated, stick powder is a worst case condition, and so is a small case. The laws of physics being what they are, ball powders and larger cases will turn in more favorable results.

But just for grins.....

Assume that you are measuring powder down to 1/10th of a granule, and that variation in bullet weight, neck tension, case capacity, etc. are giving you a standard deviation of 30 FPS. So you switch from measuring down to 1/10th of a granule to using my powder measure. Here are the actual numbers:

223/5.56, Varget. The standard deviation of 30 FPS becomes 31.95 FPS as previously shown.

223/5.56, ball powder. SD of the powder measure is .041 grains. The standard deviation of 30 FPS becomes 30.28 FPS.

308, Varget. The standard deviation of 30 FPS becomes 30.67 FPS.

308, ball powder. The standard deviation of 30 FPS becomes 30.04 FPS.

I've given you all the necessary steps, so you can make the same calculation for other cartridges if you like.

Slightly interesting. One thing is for certain, we dont all do it the same way. Some struggle more than others and some just seem to get it done regardless.

Meh. Do you really think everybody else gets similar results, with every powder out there? You're going to pretend that a guy dispensing 3031 with a Uniflow will get the same results?
Seriously, you miss the forest because of all the trees.

Exactly, thank you.

True, but I'm not much into re-tweaking the load with every new batch to account for mass density differences. Volumetric charging doesn't inherently have this batch-to-batch variation. Of course I'm being a little facetious, but the claim that energy density is more consistently correlated with mass than volume may be fundamentally flawed due to the chemical nature of smokeless powder.