Scale to scale variation

[Lucky6547]

Hi guys,
I have had some fits trying to figure out why my groups/es were not as good after switching to a new scale.
I had put a 105gr bullet on both and they read the same, so I figured they would read the same when I was trickling powder into them.
I was wrong.
“Old” scale is a newer Chinese made RCBS 10-10, “new” scale is an ohaus Lyman d-5 from the 60’s/70’s.
Didn’t realize until I decided to load up ten of each from each scale at 42.4gr, and suddenly I realized I should take the 42.4 from the old scale where I was getting good results, and put that into the new scale. Turns out 42.4 from the old scale reads 42.6 on the new scale.
So don’t do what I did...check first what a good load is on your “new” scales!
Take care,
Ken

 

[JohnKielly]

That's why I make a standard weight for all my special loads. Sometime for those in the 40=50 grainish range, I use old .22 soft point bullets & cut & drill out the point, then scratch the weight of them on the side.

 

[RegionRat]

Sounds like a set of check weights is in order.
I would run checks near zero, the middle, and max on the scale and see if the linearity is good, then do a full set of tests near the weights you use when you reload.

It's too bad the scales show a 0.2 grain difference, but should that have de-tuned the load badly? Maybe it would if the node is super narrow?

 

[Texas10]

Unless you're buying laboratory grade scales, and using them under laboratory conditions, the chances of having two scales weigh the same over a wide range of weights is about zero.

But since you still have the old scale and can compare known weights, simply updating your loading records should solve the problem easily.

You can also send your new old scale to Scott Parker for calibration. It'll take a while, but you'll have an accurate and repeatable scale when he's has his way with it.

 

[JFrank]

I find that 0.2 is about 10 kernels of Varget’ that’s a lot....

If I may offer that one should zero ones scale to a accurate check weight prior to a loading session.
Ensure that the main poise settles in the center of the V groove.

Do this on both scales at the same time.

 

[JimSC]

it is the consistency that matters. I have two electronics that measure exactly .001 grams apart from 10 grams up. One cost me 20 dollars the other 500. Been that way since I bought them, no idea which one is the closest to 10 grams but both are very precise and precision is what you need in reloading

 

[Lucky6547]

Update on this:
The ten shot group at 600 yards with the old scale was 4.32” with 2.48” vertical. 99-5x, I probably could have been better at sighting it in, and it would have been clean.

I shot the ten of the “new” scale and it was a 5.53” group, basically round group, 4.6” vertical.
I didn’t adjust the scope so that there would be fewer variations so the score doesn’t matter on this group.

So it wasn’t that it was shooting “bad”, just not as good as it used to. I was expecting high 190’s and was shooting low 190’s...

Hopefully with the appropriate setting of powder, the groups will come back.

The Chinese rcbs seems smoother and repeatable, but each kernel doesn’t move the scale. When I trickle up to the charge, and check it, it’s usually the same.
The Ohaus seems to show every kernel, but sometimes it jumps up or when I trickle up and check the charge again, it will read heavy on the second check. I have cleaned it, and the blades seem fine, no obvious flat or shiny spots.

 

[Ned Ludd]

I would also suggest purchasing a set of calibration weights. Even something as simple and inexpensive as the following set would make a nice addition to your powder weighing setup:

https://www.amazon.com/dp/B07B8J19DM/?tag=accuratescom-20

 

[Depart123]

I have a couple sets of apothecary weights (they include both metric and weights in grains)and calibrate my scale within 5 grains of the exact charge I am using. A good set of Troemner weights can be found for $60

 

[JEFFPPC]

And I thought my 10's weren't X's because I misread the wind. Live and learn.

 

[Fuj]

Some scales have too much dampening force. I use a
near original 10/10 and D-5. With a heavier calibration
weight they are equal, but as you go down into the lower
charge weights, The D-5 needed an extra kernel or two to
break that force.