Home Forums Reloading Big Game Rifles typical variation in powder throw

I've been using a REdding "precision" powder throw for some time.

typical uses are common rifle calibers. 243, 7-08, 308, etc. normal charges in the 40-50 grain range.

when I'm using "stick" powders (4320, 4350, etc) it's not uncommon for two consecutive powder throws to vary as much as 0.7gr per throw when weighed individually.

do yall see that much variation when you check it?

I see far less charge to charge variation when using spherical powders (TAC, Big Game).

just curious if maybe I need to take the whole thing apart and clean it or something.

I've been using a Redding measure for quite a while. I haven't run much IMR4350 through it so I can't say about that one. But if you're getting .7 grain swings throw to throw with the tiny kernels of 4320 there's a problem somewhere. I don't get that much variation with 3031 and 4064 which are Lincoln Logs compared to 4320.

Is your throwing technique consistent?

well, I thought it was.....

I don’t get enough variation with the ball powders to worry about out of my old RCBS Uniflow......but with extruded powders I get more. I know it has been proven to be not necessary, but I still “trickle” in the extruded powder variation. Yes I know, but it makes me feel good to weigh every charge when using “stick” powders.

That is not a bad reason for doing it that way.

I know this is under Big Game, but I have a Harrell's that I use for a 19 Hornet and 1680 powder that varies as much as 2/10th when the temperature changes. I always trickle powder now, no matter what the caliber anymore. Reloading, like shooting is therapeutic for me. Terry

I’m a trickler too, In more ways than one.

Always set mine to throw short, then trickle to what I want.

Titegroup for pistols, I weigh about 1 in ten since I’m in the middle of start and max.

What kind of scale are you using to weigh the charges? How accurate and consistent is it?

Billy Goat,

That amount of variation is pretty typical for stick powders, especially larger-granule stick powders like IMR4350, even in the best measures.

thanks John, and for the other responses.

while I love reloading, I cant confess to being a "trickler". in fact, I don't own one. When I first started reloading, my "trickler" was a teaspoon stolen from my moms kitchen. I still have the spoon at my reloading bench. (don't tell mom) =P

Once I get the powder throw dialed in, I'll "throw" 50, and then just do a visual inspection to make sure:

1. all cases have powder and
2. the powder level looks close from case to case.

I used to use an RCBS Uniflow. I spent the $ on the Redding in an effort to get more consistent powder charges long long ago, and didn't realize until recently that I haven't been getting it. =/

That said, it hasn't caused a major accuracy issue thus far. It does make me leery about using it on the upper end of the load range, through!!



I used to use a RCBS beam scale for measuring weights, but have absolutely fallen in love with a very simple Hornady electronic scale. it is stupid simple to use, and very consistent. Love that thing.

I was taught to trickle charges up to weight when I started reloading in the early 70's and have done so ever since. I have been using a Redding measure for some time now having previously had an RCBS Uniflow, I don't feel that the Redding works any differently than the RCBS. As for scales I have used many different balance beam and electronic models, my preference is the Ohaus 10-10. With the Redding/Ohaus combination I can load accurate ammunition for hunting rifles. Like the OP I see variation from throw to throw from the Redding measure, but since I trickle to weight it doesn't concern me.

A few years ago, I did an article for Varmint Hunter on scales and powder measures. Some of the test results were a bit surprising.

The Lyman digital scale was a "houseplant". It really required stable temperature conditions for satisfactory results. The Hornady balance scale was very robust and oblivious to temperature changes, disassembly/reassembly, etc.

The humble Lee Perfect Powder Measure beat the much more expensive Hornady measure.

Lest you should worry, all the devices tested were satisfactory or better.

With 2520 ball powder, the random error in the Lee Perfect Powder Measure was better than I could measure. The Hornady balance scale turned in a standard deviation of .043 grains, so 99.7% of measurements would be within plus or minus .129 grains.

With H4831SC, the standard deviation of the measurement error was .1 grain for the Lee, and .14 grain in the Hornady Lock N Load. So 99.7% of measurements would fall within plus or minus .3 grains or .42 grains respectively.

That should give you an idea of what is "normal".

These errors are entirely inconsequential unless you a shooting a remarkably fine rifle at very long range. Error does not add linearly, and there are other sources of error in the system that swamp out the effect of charge weight variation. For practically all applications, individually weighing each charge has no detectable effect vs. using a good quality powder measure.

I see what you did there.

Another factor is that a large amount of powder-weight variation (say +/- .5 grain, or even more) often doesn't make any practical difference in accuracy, except at ranges beyond where most shooters shoot. In HATCHER'S NOTEBOOK, General Hatcher states (as I recall) that .30-06 National Match ammo often varied =/- 1.5 grains in powder weight, yet shot very well in accurate rifles out to 600 yards.

The reason generally given for this sort of thing is that the most accurate powder charge for a certain bullet tends to hit the barrel node, where the muzzle is in a reasonably stationary position when the bullet exits the muzzle. A little variation in muzzle velocity of, say, .0136% (which would be the approximate variation of a .30-06 powder charge that varies .75 grains from average)in a reasonably stiff barrel wouldn't make a significant difference at 600 yards, especially when shooting iron sights.

A lot of handloaders assume that "zero" variation in powder charge automatically results in finer accuracy. It doesn't, especially at the distance most handloaders shoot--which is often 100 yards max. Other factors are far more important than a variation in charge weight of a few 10ths of a grain. But many handloaders (often older, but not always) waste a bunch of time "perfecting" every powder charge to within a gnat's weight. (I have no idea what gnat weighs, but it ain't much.)

It's far more productive to adjust other factors, both in the rifle and handloading.

Consistently better "groups" may be more directly proportional to the amount of coffee you consumed, rather than the accuracy of your "thrower".

I weigh each charge so there is no variation...because I can.

I weigh each charge too, especially when using powders like IMR4350. None of my rifles complain (in the accuracy dept.), so I keep doing it...

Yep, besides that my uniflow "cuts" longer stuff and then stumbles and pucks so I just avoid all that and it makes for a much more enjoyable loading session.

Weighing each charge certainly does no harm, and if people want to do it, I make no objection.

However, consider the following bit of math:

Random variation adds by the square root of the sum of the squares, not linearly. That's a mouthful, and may not mean much to most folks. But it has profound implications for shooters.

The 223 has a small case and is therefore more sensitive to powder variation than say the 270 or 30-06. In round numbers, a grain of powder is 100 FPS with 55 grain bullets. Typical commercial ammo has about a 25 FPS standard deviation.

So, for example, assume that you have a lab grade scale capable of measuring to the milligram. Also assume that your ammo is a bit better than most commercial stuff, and has a standard deviation of 20 FPS. Based on my experience, that's in the ballpark.

Now assume that for the sake of convenience, you want to start using the inexpensive Lee Perfect Powder Measure, and that you are using ball powder. In that case, I have measured the standard deviation of the powder measure, and it is right around .04 grains. .04 grains is about 100 FPS X .04 = 4 FPS standard deviation in muzzle velocity.

Now do the sum of the squares math: (20^2 + 4^2)^.5 = (400 +16)^.5 = 20.39 FPS.

So in that case, moving from an extremely good lab scale to an inexpensive powder measure increases that standard deviation of muzzle velocity from 20 FPS to 20.39 FPS. You'd have to shoot a really, really large sample to even show that the change had happened.

I also tested the variability of H4831SC. Of course, that is not a suitable powder for the 223, but I expect that Varget is at least close in measurement variation. In that case, the standard deviation of the powder charge is .1 grain. So the standard deviation of the muzzle velocity due to powder charge is .1 x 100 FPS = 10 FPS. Doing the math, (20^2 + 10^2)^.5 = 22.36 FPS, from a process that was formerly 20 FPS.

The day I did that math, I quit individually hand weighing charges.

The result of the math is:

1. If one source of variation is much larger (say 2X) than the others, then it alone almost completely determines total variation.

2. You will never succeed in improving a process by working on several of the weak variables. You have to find the strong contributors, and work on those. In most practical situations, the main source of variation is the shooter. So there is more truth than poetry in the coffee comment.

I've used two measures but not that one.

Variation with spherical powders, both rifle and handgun, is essentially nil. I get no more variation in weighed consecutive charges than I do in re-weighing the same charge multiple times. The only thing that has caused variation with my current measure is how much powder is in the hopper. It throws heavier, not lighter, as the hopper empties. I think this is a matter of tapping the handle also settling the powder more densely in the measure. Once some max has been hit, keeping the hopper roughly the same level by adding a little more at a time rather than waiting and doing a large refill resolves the problem

Variation with long cylindrical powders is pretty bad, enough to blow up a gun. It varies both high and low. I only ever use the measure now to load the pan for my scale with a near but short charge, then trickle up to weight.

Flake powders are worse. The absolute variation is less but the total charge is very much less causing a higher percentage deviation. An example ... I was loading 10 grains of Blue Dot weighing thrown charges. Variation was from around 8 to over 13 grains. That can blow your damned gun up and take your head off with it.

Tom

I like your math. This is how I calculate:



I'll keep weighing my charges, because it gives me a warm fuzzy feeling..

Very nice indeed.

If you like individually weighing charges, then I say go for it. A warm fuzzy feeling is reason enough.

Great explanation. There is a reason that when we’re doing a physical uncertainty analysis, if one contributor is at least ~3x larger than another, we essentially ignore the smaller factor entirely.

I never weigh or trickle charges. Thrown loads with a JDS Quick Measure gets me sub-1 MOA 10-shot groups and well under 10 fps SD, with a good load and barrel.

I've shot a number of half moa, ten shot groups from a couple of my 308's using thrown charges of IMR3031 Lincoln Logs. I've shot dozens of one moa, twenty shot groups from a number of my 308's with thrown charges of 4895, both H and IMR versions. Other ducks need to be in a row before ultra precise weighed charges show an advantage.

Could you go over the whole math thing again?





P

as the OP...... I wasn't asking out of concerns for accuracy. I get good groups from most of my loads.

I was mostly curious if something might be wrong/dirty/jacked up with my powder measure. doesn't sound like there is, since others report similar variations.

I fearful that if something wasn't working right, if it might cause an unsafe condition. since the variations seem normal, and I'm staying in the recommended load ranges, it looks like I'm not causing an unsafe condition.

so many thanks to all respondents.

My RCBS uniflow is throws ball and flake powder real accurate. With stick powder it varies between.2 and .3 grains. I could be wrong but it seems Like Alliant meters better than Hodgdon, like Alliant kernels are softer?

Over the decades of reloading I've learned that with any extruded powders, I need to weigh, especially if I am pushing maximum loads.

Sometimes in the late 1980's I was loading 7X57 for a Win 70 featherweight I was using for Antelope hunting. I was pressed for time and decided to use my powder measure for dropping the charge. I was using an extruded powder (I forget which) and was dropping the powder from one of my two powder measures (Lyman and Hornady). I would measure the drop till I had the correct weight and then drop 10 and measure and drop 10 more. I went to the range to do a sight in, after a few rounds I had one shot that was noticeably more recoil. The shot had gone over 2" higher that the previous group and the bolt was difficult to open. When I managed to get the bolt open and extracted the case, the primer fell out of the case. I stopped shooting that rifle and went on with others I had brought to the range. When I returned home I pulled each of remaining rounds and did a weight measure. I seem to recall it was 11 rounds that I had left and all but one were .1-.2 gr close to the desired weight... but the one dropped way over max.

I decided to experiment and use the powder measure to drop the powder I had used for the 7X57 and weigh each of the 30 tries (not reloading but just to see how the drop went) and found 28 were close. But two dropped over a grain and beyond the max range.

From that day on I've only used the powder measure to drop ball powders while doing a 10-and-weigh-one. If I use a powder measure to drop extruded powder for convenience, I will always weigh the drop. If I'm close to a max load, I will still weigh, even with ball powers. So far, I've not had a repeat of that experience. Once bitten twice shy.

I get similar results to what you saw with powders like 4350, it doesn't sound like anything's wrong with your powder measure.

In the last few years I have loaded literally thousands of rounds of 243 ammo for several shooters. I use my Neal Jones powder measure and load Varget. I weigh each charge to assure quality control. The powder measure is of excellent quality, and I am by now very practiced. If I use the same technique every time and keep the hopper from running empty, the charges are remarkably consistent, generally withing .1 grain. However, if I do not use the same technique religiously, that is not the case. In addition, sometimes powder will bridge up in the measure and then charges aren't so consistent. I have seen as much as a grain or two stick in the tube. Sometimes half the charge sticks in the tube. The bridging problem probably doesn't happen with ball powders.

I used to think I threw a good charge until I bought the RCBS chargemaster. WOW what a new pleasure in loading. With my shaky shakes the trickler would throw .5 grains all by itself. W. Bill

interesting and illuminating .
thank you

This afternoon I shot fifty rounds of 308 Winchester I had assembled in some new brass I'm trying out. The powder was IMR3031, long stick kernels for those who don't know, with charges thrown directly from the powder measure. The powder charge and cartridge overall length were not tuned especially to this rifle, rather it's a baseline combination that I've found to generally shoot well in a 308 rifle if the rifle will shoot anything well. The groups were five shots each, the largest two being 3/4 moa with the rest 1/2 moa +/- a tiny bit either way. This is from a bone stock Rem 700 with their varmint weight barrel.

Thanks MD and denton. The math is especially illuminating.

My experience as well. I would say regarding stick powders that if you get used to doing a double tap it eliminates the big fluctuations for me. I will also say that I record a micrometer setting on the measure and load without a scale from that moment on. I played around with a lot of different powders in the 47 or 49 years I've loaded centerfires, and my experience has been that velocities are more consistent from lot to lot using volume than weight. I also have always tried to find loads that group well with large changes in charge, as conditions, powder lots, temps. are always changing, if I have a load that shoots .4 with 36 grains and 1 MOA with 36.2, I want nothing to do with it. I did this years before I knew what a velocity node was, but I was coming up with the same results.

When I see big changes in velocity when changing lots of powder, I see much smaller changes in volume than in weight.

Do you have anything to add about that, Denton?

That's an interesting observation. I haven't looked for such an effect, but it may well be there.

Everybody assumes that the scale tells the truth, and the powder measure is an approximation. The fact is that in some circumstances, some powder measures are better than some scales.

Yes, you can get lodging in a measure. And you may also get small quantities of powder in internal crevices.

But a balance scale (reliable as it is) can get dirty or dry pivots, and reloader style electronic scales are subject to temperature and power line variations. Add to that the fact that the gravitational constant is not the same all over the Earth, varying by a few to several tenths of a percent, and you may have good reason to doubt your scale.

Only The Almighty gets perfect information. The rest of us have to put up with approximations. All measurements are lies, but some of those lies are useful.

Something close to 30 years ago I had a lot of reloading product to review and 3 items included powder throwers, one from Redding, Simplex and RCBS.
I weighed a lot of charges at 10 throws a piece per powder charge using a range of ball and extruded charges from very fine to Surplus 4831 which was the most coarse I had at that time.

The Redding was the most accurate but some deviation was noted in all 3. I typed that article back in the black and white, Pre - PC days, so don't have a copy but do recall the pecking order as Redding, RCBS and Simplex running 3rd.

John

A little update about thrown charges from my range trip this afternoon:

I had assembled fifty rounds of a mild target load to fireform some new WW brass in one of my 308 rifles, a Rem 700 5R Milspec. Part of the purpose was to also check out a couple of scopes. The load used a Rem 9 1/2 primer, the new WW brass, a Hornady 168 BTHP and thrown charges of 39 grains of IMR 3031.

The first scope was an old Vari-X III 2.5-8x36, old enough to have friction adjustments. I boresighted it at 100 yards, set it to 6x and put five shots into 5/8". This group used cartridges marked for so-so runout. I adjusted the scope to move POI to horizontal center. The next ten shots, using cartridges with utility grade runout, went into 5/8".

Later in the session I mounted a Vari-X III 3.5-10x40, one from the click adjustment, Multicoat-4 era. Boresighting and shooting three rounds made a sub 1/2" group so I dialed for center and then added enough elevation to go to 300 yards. For a target I put a blank sheet of letter size paper up at 300, went back to the line and set the scope to 3.5x. Three shots made a nice group, just under 1.5" wide and 0.5" tall. I was using good runout rounds with this scope.

Some guys had put up a squared off head/torso silhouette next to the 300 yard board. The "head" was a square tab 3 3/4" on its sides. With the scope still set to 3.5x I rang off seventeen consecutive head shots. The bullet splashes fell within one moa horizontally, 2/3 moa vertically.

So much for weighing charges and high magnification scopes for most deer hunting.

(That ought to start something. )

I do too....

While unscientific, in one cartridge in particular, I use the same volumetric setting on the 3 BR Redding measure (stick powder) going from lot to lot and the load has always been within 25 fps. of the last lot.
Granted, its a load with 100% density, slow for the cartridge and the cases are on par for capacity. I've done that the last 12 pounds that span over 7 years production time.

Just a sample of one. There are only two cartridges I know/remember where the settings are and the other is a handgun round.