scale calibration

[reubenhwk]

I loaded some grendel loads today and I'm concerned my scale is inaccurate.

I used the balance beam from lee precision to measure out 27.5 grains of benchmark for some 100 grain barnes ttsx. I zeroed the scale properly and measure each load meticulously, but later, to verify, I used an electronic scale to measure the loaded cartridges, but I got unexpected results.

So I weighed the loaded cartridge, then subtracted from that a spend cartridge, I get 134.5 grains. I was expecting to get 127.5 (100 grain bullet + 27.5 grains benchmark). Seems like the loaded ammo is 7 grains too heavy or my electronic scale is wildly off.

You can't weight my ammo, but you can weight a quarter (if you'd like to help).

My electronic scale says quarters (25 cents) weigh 91.6 grain on average. The US mint says quarters should weigh only 87.49 grains (+ or - 1% maybe). What does your scale say?

Thanks in advance.

[rasp65]

The quarter I have weighed 87.3 gr. Did you calibrate your scale?

[reubenhwk]

The quarter I have weighed 87.3 gr. Did you calibrate your scale?

Yes. My electronic scale is the AWS-100. It has the 100g calibration weight. It passes calibration, but it doesn't seem to be accurate with very small weights.

Thanks for weighing that quarter.

Anybody else find time to weigh one?

[Drifter]

On my RCBS Charge Master, a 20-year-old quarter weighed 87.1gr every time. A 5-year-old state quarter weighed 87.8gr repeatedly.

[mlmiller1]

I suspect two things. One, your electronic scale is off. Two, unless you weighed & batched your brass before loading, you cant expect to weigh one pc of brass & think another one should weigh the same. If you are really worried, pull the bullet, weigh the charge.
One more thought, did the empty brass you weighed have a primer?

[reubenhwk]

I suspect two things. One, your electronic scale is off. Two, unless you weighed & batched your brass before loading, you cant expect to weigh one pc of brass & think another one should weigh the same. If you are really worried, pull the bullet, weigh the charge.
One more thought, did the empty brass you weighed have a primer?

Yes, the empty has a spent primer.

I guess I pull a few of the bullets and weigh the charges again to be safe. Maybe I'll pull them all and reduce the load a work up like I'm supposed to do anyway.

[Hoot]

As someone who worked in Test Engineering, it has always troubled me that on several digital reloading scales I've used, they came with only one, heavy calibration weight, yet I used them to weigh powder charges that were 1/10 that calibration weight. Is that standard procedure? Seems to me that you would check the calibration with a weight in the area of what you're going to use the scale to measure. Do the manufacturers assume the average reloader is too dense to handle multiple calibration points for the same piece of equipment?

Hoot

[bwaites]

All my digital scales have at least a two step, two weight process for calibration, including the RCBS, which has 2 50 gram weights. Admittedly, I would like lighter weights for calibration as well!

It does seem strange that scales supposedly acccurate to .1 grain should use such heavy weights for calibration!

That said, when I've tried several different electronic scales with the same thrown powder charge, I've never seen more than .2 grains variation, after each was properly calibrated by their procedure. Assuming that the error is .1 grain high on one and .1 grain low on the other, that's within the error margin.

[Hoot]

All my digital scales have at least a two step, two weight process for calibration, including the RCBS, which has 2 50 gram weights. Admittedly, I would like lighter weights for calibration as well!

It does seem strange that scales supposedly acccurate to .1 grain should use such heavy weights for calibration!

That said, when I've tried several different electronic scales with the same thrown powder charge, I've never seen more than .2 grains variation, after each was properly calibrated by their procedure. Assuming that the error is .1 grain high on one and .1 grain low on the other, that's within the error margin.

Despite my earlier statement about my concern, that has been my experience also.

I guess it is a testimonial to the state of the art in load cell design and manufacturing.

Hoot

[Whelenon]

You get what you pay for, as a gift I got a cheap digital scale, and took it back. It wouldn't hold zero/tare and couldn't get consistent loads. I went back to my beam scale, still want to get a digital scale but a good quality unit.