Different measurements from different powder scales

doowroh

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So I've got three scales. All measure differently, with a margin of error somewhere within ~0.3ish grains. Each scale seems quite repeatable, as long as I don't compare one to the other.

My main goals are to load for hunting, but the idea of longer range target shooting is really starting to appeal to me.

My first scale was a very clean, used RCBS 5-10. I think the seller switched the powder pans before shipping it, so I couldn't get a good zero. I re-calibrated it with some #9 lead shot and it's been good to go since then. The knife edges appear to be in great condition.

My next scale was a used, older, less than pristine Lyman D7 that I bought for $10. It was missing the beam lifting/storage mechanism, but other than looking dirty and well used, the knife edges seems to be in great shape as well.

For the beam scales I made a leveling plate. I used a 1/4" aluminum plate, some nut-serts and some spare/surplus bolts screwed through the nut-serts to get adjustable "feet". I level the plate on my workbench, level the beam scale at zero, and then don't touch it for the rest of the loading session.

My most recent scale is a Hornday electronic LnL Bench Scale. I warm it up for a few hours before using it, it's quick, and most of the time it seems accurate & repeatable. I occasionally find this scale measure the same item differently (within ~0.2 grains) if I lift it off and check a couple of times. Although that's usually on lighter things, like primers etc.

So my questions are:

1) why are my measurements different between each of these scales?
2) if each scale measures differently, which scale should I use/trust?
3) should I bias/true the beam scales (by adjusting off-zero) to sync the scales up?
4) does it even matter, as long as each scale is repeatable?

Thanks for your thoughts/experience.
 
use one beam as reference. electronic can vary with quality, air pressure( forced air on or off) other electronics in the vicinity, level plate, battery life. but they are quick. verify with beam periodically to ensure consistency.
 
Both electronic scales I have came with two calibration weights. They have a calibration mode where you put the weights on them as directed and presumably it calibrates.

But in general, calibration weights are the best way to find out how 'true' and accurate a scale is. Ideally calibration weights that weigh nearly the same amount as the item you want to measure.
 
I am going to go with your #4, does it matter if it is repeatable. And my answer would be no. If your rifle shoots a load accurately and a certain scale says it weighs 45.5 grains, it doesn't matter if it actually weighs 45.8 grains. All that matters is your scale will let you consistantly come up with the same load.
 
you get what you pay for.
Try to find one that is certified. And calibrate all of them with the same check weight.

This is correct. Loading scales, unless you want to spend a lot of cash, are made to be "rudimentary comparators"...some of them you get lucky and they are bang on for the reading you get but as in your case, it's not always the case. Reloading scales are made to be affordable to everybody that wants to get into the hobby.

It is for this very reason every loading book from every powder or bullet manuf. recommends in the very first paragraph of the first chapter in all their books to "start low"...this covers their butts as to inexpensive scale variance's...then you can more or less suite yourself as to when you reach an acceptable pressure tolerance for your gun.

Post #10 is also right, once you reach a level of acceptance in your own mind continue with that scale and load formula forever...no variances of component manuf., if you do start at the beginning again....

And no, they are not junk to be disposed of , the next one brand new right out of the box, might be worse!!!
 
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