Scale inconsistencies?

[Rocketvapor]

When checked (often) at or near my target weight, both Beam and Digital compare quite well.
Here's 8 grams (40 carats, 123.459 grains) and 6mm Hagar cases converted to 22 Nosgar, sorted to 125 grains (+/- 0.5 grains). Sorting also got me a bunch @ 126 grains. Ready to prime once I sort out some primers
Sorting is a little faster with a digital. This scale has been pretty good for about 3 years.

 

[redrockranger]

Why would a beam scale and a digital scale sometimes yield the same results and sometimes not? (Details below; yes, I am going to get a set of fine check weights.)

The 2 scales: I just started brass cartridge handloading. For 16 years prior, I shot a Savage 10ML-II smokeless muzzleloader, which I did with the care appropriate for all handloading, including lots of reading and discussion to understand applicable principles internal and external ballistics. For those 16 years, a Lee 100gn beam scale had enough precision for 60 to 85 grain loads to consistently yield 3/4 MOA groups from my Sav10ML. When I bought the Hornady L&L reloading kit 6 weeks ago, it included a Hornady 500gn digital portable/pocket scale with .1gn precision.

I expect to upgrade to a more precise auto trickler scale down the road, but I want to understand what I observed in the meanwhile.

First batch consistent: For the first 30 cartridges I loaded, I leveled and adjusted/calibrated the Lee balance beam to level at 0.0gns, then verified the Hornady digital scale using the 10g (154.324 gn) checkweight. Next, threw the charges of VV N140 with the Hornady powder measure (also from the kit) about .5 to 1 grain under and placed them them on the Lee beam scale to trickle up to weight (23.5 to 24.5 gn test loads). Lastly, I verified each charge on the Hornady digital scale. The two scales were consistent.

Second batch inconsistent: A few days later, I repeated the same process for 30 more loads. However, this time the two readings on the two scales differed by ~.2 grains on each charge. I zero calibrated the Lee beam multiple times, checked for unevenness under each scale, re-oriented the Lee to make sure hidden bench slope was not the issue, and used the check weight to verify the Hornady scale (it always read 154.3gn). Since the check weight exceeds the Lee weight capacity, and the Hornady checked fine, I assume that the Lee scale was off that day--which I had thought was less likely than a digital scale wandering. In the end, I relied on the Hornady digital scale readings and disregarded the Lee results.

Why? Any thoughts? How or what could cause a beam scale to yield good results one day and erroneous results (even after calibrating) on another day?

Personally. My experience with a Pact Digital and a RCBS 750 digital scale and a RCBS 505 balance beam i went strictly to the RCBS 505. To many variables with the electronic stuff leads to to much double checking and recalibration of the electronics.

 

[Rocketvapor]

Reloading consists of several sub-processes.
Measuring powder accurately is just one of many that can introduce errors at the target.
Making one sub-process insignificant eliminates it's effect on the final product.
Undetected errors in the charge weight due to scale errors and drift AT THE TARGET WEIGHT contribute error to the final result.
Drift, either at zero indication or scale factor at the target weight, or linearity error between calibration point and target weight are error sources that are easily detected, and corrected before tossing powder into a case.
If your digital calibrates well @ 50 grams, but has a linearity error @ 30 grains, fudge the 50 gram calibration a little to make the target reading dead nuts.

A beam scale in good repair and used properly can easily provide 0.1 grain charge accuracy.
This is USUALLY GOOD ENOUGH.
So can a digital, used properly. The digital has two advantages over a beam scale.
1) it's usually faster.
2) sorting unknown weights of cases, bullets, primers is much easier.

Many cheap digital scales have a built in "Auto Zero" which can be good or bad. Just know when it is happening. Try and determine the type of error that is causing your issues. External influences like electronic interference, drafts, or temperature can be fixed. I charge for about 10 to 15 minutes AFTER the HVAC shuts off. Take a break when it comes on.

Some digital scales advertise more resolution than you might need. Like the 0.01grain scale in another thread. Who NEEDS 0.01 grain resolution? Don't look at the last digit or realize that it's only there to give you confidence in the next to last digit.

The whole point in accurate reloading is to make error sources for each sub-process INSIGNIFICANT.
Insignificant to your desired precision.

 

[BringBackThe80s]

Personally. My experience with a Pact Digital and a RCBS 750 digital scale and a RCBS 505 balance beam i went strictly to the RCBS 505. To many variables with the electronic stuff leads to to much double checking and recalibration of the electronics.

I have been thinking I might get a 505 until I can and feel like springing for an auto trickler setup.

 

[BringBackThe80s]

... Some digital scales advertise more resolution than you might need. Like the 0.01grain scale in another thread. Who NEEDS 0.01 grain resolution? Don't look at the last digit or realize that it's only there to give you confidence in the next to last digit.

The whole point in accurate reloading is to make error sources for each sub-process INSIGNIFICANT.
Insignificant to your desired precision.

I agree about the principle, I just do not know yet about where the threshold of significance is for each of the factors. For the moment, my goal is loads that consistently shoot 1/2 MOA. (I think maybe that is realistic, as my first batch of handloads produced 8 groups between 5/8" and .85".)

I imagine that charge weight precision matters more the smaller the intended charge weight and the longer the distance. A 0.1gn variation in a .223 is nearly a 0.5% fluctuation; in 300PRC, it's barely above a 0.1% fluctuation.

So, I have a lot to learn. Meanwhile, I have tried to start with a moderate cost/quality setup, then upgrade pieces as I gain experience and identify where more precision will matter most.

 

[Homerange]

I agree about the principle, I just do not know yet about where the threshold of significance is for each of the factors. For the moment, my goal is loads that consistently shoot 1/2 MOA. (I think maybe that is realistic, as my first batch of handloads produced 8 groups between 5/8" and .85".)

I imagine that charge weight precision matters more the smaller the intended charge weight and the longer the distance. A 0.1gn variation in a .223 is nearly a 0.5% fluctuation; in 300PRC, it's barely above a 0.1% fluctuation.

So, I have a lot to learn. Meanwhile, I have tried to start with a moderate cost/quality setup, then upgrade pieces as I gain experience and identify where more precision will matter most.

Other things matter more than absolute charge weight accuracy. Load development is a journey where many things matter however finding a wide node mostly eliminates the need for precise powder load accuracy.

Oh and BTW, you should refer to the abbreviation of grains correctly as gr not gn.

 

[Rocketvapor]

I suggest a good calibration weight, maybe 2 grams, or pair of them to compare and inspect for damage.
Store one and ONLY use it to check a working weight.
IF you want to weigh accurately to 0.1 grain @ a target load of 20 to 30 grains, then consider a cal weight with an accuracy tolerance a fraction of your goal of +/- 0.1 grain, 6.48 milligrams.
An ASTM Class 6 20 gram weight has a tolerance of +/- 3 milligram, or about half of your error budget.
Good enough for a one tenth scale.
There are some gn class f weights and sets from several trusted manufacturers in case you would rather work in grains and not grams. Calibration sets from the various reloading companies might be OK but I could not find an accuracy specification. For example the RCBS Delux set has weights from 200gn to 0.5 gr.

The 0.01 grain scale in the other thread (still a load cell scale though) has a 3 point calibration.
"Whether you are loading for .22 Hornet or 416 Barrett, the 2g, 10g, and 50g weights (representing 30.86gn, 154.32gn, 771.61gn respectively) calibrate the scale using a linear calibration method that is unique among reloading scales. "
I assume the cal weights are good enough.

 

[BringBackThe80s]

Keep your cell phone, at least 6 feet away from the digital scale (and any other object that sends/receives/or has magnet(s) involved.

That's a good suggestion. I am not certain it was quite that far away.

 

[AzMandella]

As a newby myself I did alot of research and since I did not want to spend $500 or $1000 on a scale I decided on the Ohaus 505 .

Reloading Scales Reloading Scale 5-0-5

Reloading Scale 5-0-5 is part of the Reloading Scales family of products.

us.ohaus.com

 

[DirtySteve]

As a newby myself I did alot of research and since I did not want to spend $500 or $1000 on a scale I decided on the Ohaus 505 .

Reloading Scales Reloading Scale 5-0-5

Reloading Scale 5-0-5 is part of the Reloading Scales family of products.

us.ohaus.com

I sure wish they still made the 5-10 or 10-10 scales..

 

[Homerange]

I sure wish they still made the 5-10 or 10-10 scales..

Mine 505 is ~45 yrs old and retired now the CM1500 has taken over its duties and made loading much faster.

 

[AzMandella]

Heres a Good deal for Ohaus digital scale . Only 1 left

https://www.tequipment.net/Ohaus/SPX223/Scales/Weight/?b=y&v=7855

 

[AzMandella]

Another good deal

https://www.tequipment.net/Ohaus/SPX123/Scales/Weight/

 

[JFrank]

That's a good suggestion. I am not certain it was quite that far away.

I have a electric scale that claims .01 resolution and indeed does weigh quite well except for small drift of for example .01-.03
When I place my cell phone right next to it there is no effect whatsoever.

 

[Kracken McGraw]

I’m using a couple of cheaper Grizzly Bald Eagle( discontinued) scales that read to .00 and can get within .02 pretty easily. I know what my tare weight is supposed to be with the pan off and can watch this number if it tries to drift some. Both scales won’t drift at the same time so that speeds things up, plus I like to double check myself. It’s also a lot faster and less clumsy for me over the beam scale, but I will always have one for a backup.
Of course if I had the funds when I started back up again, I would of have been better off just buying the FX-120.

 

[JFrank]

I agree about the principle, I just do not know yet about where the threshold of significance is for each of the factors. For the moment, my goal is loads that consistently shoot 1/2 MOA. (I think maybe that is realistic, as my first batch of handloads produced 8 groups between 5/8" and .85".)

I imagine that charge weight precision matters more the smaller the intended charge weight and the longer the distance. A 0.1gn variation in a .223 is nearly a 0.5% fluctuation; in 300PRC, it's barely above a 0.1% fluctuation.

So, I have a lot to learn. Meanwhile, I have tried to start with a moderate cost/quality setup, then upgrade pieces as I gain experience and identify where more precision will matter most.

Here is reality,
my charge window is .4 grains
I tune to .1 grains for long range competition
.1 grain of Varget equals 6 kernels of powder so within this window I have 24 kernels of powder.

I believe a charge master lite will accurately and consistently resolve .1 grains, perhaps @jackieschmidt will weigh in on this, ( no pun intended)

 

[AzMandella]

Another good deal

https://www.tequipment.net/Ohaus/SPX123/Scales/Weight/

I went ahead and grabbed this one .

 

[Rocketvapor]

SPX123 Readability

0.001 g

Linearity ±

0.003 g

Repeatability (typical)

0.002 g

Span Calibration Mass* 100 g
Linearity Calibration Mass 50, 100 g

Readability in Grain (grn) 1851.88 × 0.02

 

[BringBackThe80s]

When checked (often) at or near my target weight, both Beam and Digital compare quite well.
Here's 8 grams (40 carats, 123.459 grains) and 6mm Hagar cases converted to 22 Nosgar, sorted to 125 grains (+/- 0.5 grains). Sorting also got me a bunch @ 126 grains. Ready to prime once I sort out some primers View attachment 1305027
Sorting is a little faster with a digital. This scale has been pretty good for about 3 years.

I am curious about your pictures, as I have not previously seen anyone use a cushion or liner on top of the scale plate when weighing things. Is that something you always do or unique to those instances?

 

[Rocketvapor]

When using my Mass Standards, they do not touch a metal pan, fingers are gloved.
Price Class 1 weights
Working weights, no worry.

The 100 gram ASTM Class 1 has a tolerance of 1/4 milligram. Cheaper M1 100 gram weights when compared to +/- 1 milligram (double substitution) can be combined for 500 grams at better than
Class 4 level (+/- 10mg).
and so on and so on