Kernel of powder accuracy

Yeah, two grains is a lot. I can see the 1500’s being off a tenth or two with their auto zero “feature” but it would be pretty difficult for them to throw 2.0 off unless you have messed with the parameters or something is broken.

https://www.youtube.com/watch?v=JmxBSOOL7Ks

But I agree, if you laddered your load, even +/- .1 won’t be a deal breaker at moderate ranges.
 
Apologies I mistyped . I meant .2 grains.


The RCBS is plus or minus .1 grains. That means if you are weighing 10 charges at 44.0 grains one round could be 43.9 grains and the next 44.1.

ever wonder why when chronoing the exact same powder loaded in cases prepped the exact same way one group may have a ES of 20 the next a ES of 50 ?. I have, and I know what a 50 FPS velocity change can make in the vertical displacement at mid and long ranges. I have seen one 5 shot group have no more than 10 or 15 FPS variation. The next group with the exact same load give me a 50 or more spread. Velocity directly impacts barrel harmonics and vertical dispersion. I doubt anyone will argue with that. My goal is to elliminate velocity changes from round to round as much as possible. I can't control the wind or mirage but I can try and get my ammo as precise as possible.

Anyone who has ever been on the scoring crew at NRA match has used scoring gages to determine if a shot is on the line or over it. 1 or 2 points has decided the winner in many matches. I have scored targets and seen a point or two drop over a shot being 1/10th inch high or 1/10th inch low and at times on the same target. Some of those were my own targets. There are a lot of factors that can cause that and I am not saying that velocity was a factor in each one, but I cannot rule it out either just looking at my own chrono results

Not saying everyone needs to do precision loading. But for me it cannot hurt to remember it only takes 4 to 5 kernels of extruded powder to equal .1 grains and .1 grains will affect velocity
 
Last edited:
Not saying everyone needs to do precision loading.
Click to expand...

That’s why I built the device in #17, to have +/- 1 kernel changing ability and why I still use the CM 1500’s and just regular powder measures without trickling at times too.

There are lots of times where the increase in precision of charge weight will go unnoticed and would be a complete waste of time but I suppose you need the ability to charge to that degree of repeatability to know if that’s the case or not.
 
There are lots of times where the increase in precision of charge weight will go unnoticed and would be a complete waste of time but I suppose you need the ability to charge to that degree of repeatability to know if that’s the case or not.
Click to expand...

I agree. I am not sure if I will always use this on just practice ammo but for the match rounds it sure can't hurt and might even help
 
One thing about competition is that if you think it helps or think it might hurt, it will effect your mental game. There are folks that wear dirty underwear because they think it helps and for them, they are right.
 
Looking at this image of a 502 I see grains set to the five grain mark on the left side. The right side is for 0-5 and tenths of a grain. Each of the smallest marks is 1/10 of a grain. You would have to further divide each of the smallest tic marks into fifths to represent grains of Varget. I do not envy your task.

Bill
 
You would have to further divide each of the smallest tic marks into fifths to represent grains of Varget.
Click to expand...

You don’t need any indicators for a repeatable measure on a balance. If what you are going for is repeatability of dropping the same charge it doesn’t matter that you have hundredth of a grain mass accuracy, when resolution is all you are after.

Once you have a setup that can repeat the same mass to a kernel, you can tell where you are within the tenth by averaging 10 charges it you feel like it though.
 
Looking at this image of a 502 I see grains set to the five grain mark on the left side. The right side is for 0-5 and tenths of a grain. Each of the smallest marks is 1/10 of a grain. You would have to further divide each of the smallest tic marks into fifths to represent grains of Varget. I do not envy your task.
Click to expand...

It is not difficult at all. I am not trying to trickle to 44.13 grains or some such nonsense. I am just trying to make sure it 44.1 not 44.2 or 44.0.

Do the pointer extension mod the pointer, I used part of a straight pin and some epoxy. Then mount the phone/camera so it is focused on the pointer and scale and use the camera to magnify the pointer. This eliminates any parallax issues. Do NOT use a jewelers file on the blades or oil the ways.

Clean the blade and the ways of the scale with rubbing alcohol and a lens cleaning cloth. Bounce the beam a couple of time to make sure the scale is not binding and it returns to zero each time. Set your powder to your load in tenths of a grain. Throw the initial load using a powder throw or a autotrickler of some sort. I recommend throwing a tenth low. It is easier to add a few kernels than take the pan off and remove them. Then just trickle till pointer is on zero.

It is very easy to see if the needle is on the zero mark using the modified scale. Once on zero I will bounce the beam once or twice to ensure it returns to zero. If I trickled a bit over I take the pan off and use a dental pick to remove one or two kernels. As long as you don't over trickle it takes maybe 15 seconds longer than just using the RCBS to throw to weight and is much more accurate. A single kernel of stick powder will move the pointer appx a needles width, but like said all I want is my load to be consistent to the 1/10th not to the 1/100th.

If I am going for a charge of 44.1 I am confident it will be no more than 44.08 - 44.12 which is much better than having a charge that might be 44.0 to 44.2 which is the standard resolution and accuracy of a electronic powder scale
 
Last edited:
hounddawg said:
I have been mulling over getting one of these https://www.amazon.com/uxcell-3100RPM-Vibrating-Vibration-Massage/dp/B00AKWRWRW to mount on a board to do a entire box of ammo at a time ever since Unclenick first posted about powder "packing"

For those who do not think .2 grains don't matter that is fine. As long as you are happy with your ammo's accuracy then there is no reason to try and improve it's consistency any farther. You can save yourself a lot of time and money and just use a powder throw like the 100 yard benchrest crowd does. Even a 25 dollar Lee can throw that accurate.

As far as a lab grade scale why would I want to spend 500 dollars when what I have can detect down to the point where it reacts to a single grain of powder? I can use that money toward a new .224 Valkyrie build later this year

edit - BTW a Gempro 250 has .02 grain accuracy for less than 150 dollars if you want electronics. .02 grains is about 1 kernel of varget
Click to expand...

I don't know the answer to these so will ask. Does each single grain of powder weigh exactly the same? And if your data calls for say 40 grs of IMR4064, do you weigh it all one grain at a time? Doing that, how much improvement in accuracy do you get and how long does it take to load a box of ammo?
 
I don't know the answer to these so will ask. Does each single grain of powder weigh exactly the same? And if your data calls for say 40 grs of IMR4064, do you weigh it all one grain at a time? Doing that, how much improvement in accuracy do you get and how long does it take to load a box of ammo
Click to expand...

the best answer I can give you on this is it takes 4 to 5 kernels of Varget to weigh .1 grains. IMR 4350 was about the same. You can perform some tests on your powder of choice. On the accuracy improvement I have no idea. What I am doing is trying to eliminate the odd round that is 50 or 75 FPS higher or lower than the rest of the rounds. It is just common sense and physics that a round that is traveling 50 FPS faster or slower than the other 19 is going to be hitting higher or lower on the target and the farther out the more pronounced the impact difference will be
 
Last edited:
here is a recent chrono test I did, what I hope to eliminate are the extremes. I won't know whether this will be effective until I do a few range tests using the new method

24.7 69Gr 2886
24.7 69Gr 2855 ES 107
24.7 69Gr 2923
24.7 69Gr 2917 MIN 2962
24.7 69Gr 2949 MAX 2855
24.7 69Gr 2904
24.7 69Gr 2904
24.7 69Gr 2936
24.7 69Gr 2923
24.7 69Gr 2898
24.7 69Gr 2936
24.7 69Gr 2923
24.7 69Gr 2917
24.7 69Gr 2898


24.4 69Gr 2861 STDEV 14
24.4 69Gr 2886
24.4 69Gr 2855 ES 49
24.4 69Gr 2855
24.4 69Gr 2879 MAX 2898
24.4 69Gr 2861 MIN 2849
24.4 69Gr 2873
24.4 69Gr 2873
24.4 69Gr 2879
24.4 69Gr 2849
24.4 69Gr 2886
24.4 69Gr 2873
24.4 69Gr 2898
24.4 69Gr 2879
 
Now you have a scale that measures to the hundredths of a grain but is inaccurate (or you would be using it to weight your charges) backing up a very repeatable beam scale that can not determine to the hundredths of a grain. I chose to buy a scale that had acceptable accuracy and repeatability. Lets do some math now. The Gempro is $140 on Amazon the 502 is $165. $305 in your setup. $500 in mine. As long as we are both satisfied its a win win.
Click to expand...

That is a odd way of looking at things. Why would the beam scale be inaccurate? If it is leveled and zeroed I would put it up against electronic even ones costing ten times what yours did. Alos why would do you think the RCBS CM be useless? I still use it to throw rounds for AR 15 plinking and while I could throw the initial charge on a powder throw of which I own 2 I find it more effective to use the RCBS and it will get me within a few kernels of target weight. If I had a lab grade electronic scale that cost $5000 I would still be throwing the initial charge on the RCBS because it is easier and faster to add a couple of kernels than trickle the entire charge

I would wager that just about everyone on this board has a beam scale on their bench and a smart phone in their pocket. Which would be the more cost effective, accurizing what they already own or going out and spending several hundred (thousand) dollars on a electronic
 
Last edited:
Hounddawg have you ever verified your claim of 44.08 to 44.12?
Click to expand...

Balance beam scales work by moving a known weight(s) on a beam to counterbalance the weight on the other side of the pivot. Gravity is a pretty consistent as far as I know. As long as the weights on a balance beam are not modified and the scales knives and ways are not damaged there is nothing that can go wrong or cause them to be out of calibration. Of course cleanliness is next to godliness and a dusty dirty sticky blade or a cat hair in the ways can cause the beam to bind or stick when pivoting. That is why you should clean the ways and blades with alcohol and a lens cleaning cloth or something non abrasive and residue free before zeroing and test it by bouncing the beam a few times to make sure it is not sticking

I can add or remove 1 kernel of powder and see my beam move off zero when weighing a charge which is more than I can do with either of my electronics. Also I can load 4 - 5 kernels and move the beam fine sdjustment weight to .1gn and scale pointer will return to zero. If I bounce the beam a couple of times and it returns to zero each time that is good enough for me.
 
Last edited:
I was an instrument tech for 40 years and am well aware of the properties of a beam balance. Ohaus mechanical scales list that scale as "Best in Class." The readability is .1 gram. .02 grains = .00129 grams. I have not been able to find a .001 gram mechanical beam scale. If one existed it would be cost prohibitive. Like $5100 for a Prometheus. By the way how accurate is the Prometheus?
"The Prometheus is typically within 0.1 grains of the desired charge weight the scale is set to. This means if you adjust the scale to 40.0 grains, it will typically produce a charge within 0.1 grains of the setting." What is its repeatability? "No Prometheus Gen II has ever left our facility without being able to resolve a single kernel of Varget. Many users feel confident they can "call the charge" to half or even quarter kernel repeatability." I am confident you may be approaching the ability of a Prometheus. I seriously doubt you have exceeded it.
 
As long as each load is more consistent than what I got with my RCBS electronic scales then I am happy. The real test of how much precision is really needed will be done at the range and I won't know that until this &^$%&^ snow goes away. I have managed to get down in the single digits on SD on some of my testing just using the RCBS CM. I want to see if this methods gets me there more often. If it does then great, if it doesn't the beam scale will go back on the shelf and I am out an hour of labor and a dimes worth of epoxy
 
Last edited:
In my preliminary testing a .1 grain of cfe223 is worth about 5 fps. So getting real loose here .02 grains is worth 1 fps. I have my 223 SD down to about 10-11. Any further improvements must be in me and the brass. I read the warehouse again which is summarized here.. They disagree with some very popular opinions. And again they are only concerned with 100 yards and no chronographs.
 
@jugornaut- I think a lot of consistency depends the powder, the bullet and the cartridge. For my in .260 Rem H4831SC is flat as a pancake in velocity for per tenths grain spreads for 140 grain bullets. Was the same with Varget and .308 168 SMK's. I am still hunting with this .223 but I did get 4 into one hole and the 5th within 1/4 MOA @ 200 with one group from the 24.7 load data above. One 5 shot group does not make a load however

Lots of factors in this hobby, some science and some voodoo and dancing at midnight on the full moon
 
Last edited:
You must log in or register to reply here.
Back
Top