Calibration weights – a confession and a word of caution

[UL1700]

I started shooting F class in 2017 / 2018 and quickly realised that accurate wind reading takes many years to learn but a well-tuned rifle takes months, so I embarked on producing a 6br then Dasher then SAUM for my wife and a Ftr rig in 155.5 and 200.20x variants for myself. Both rifles were highly accurate and when conditions were in our favour we would walk away with a medal and even an OPM or two. During this time, I quickly realised that the old 505 balance beam whilst good for accuracy was never going to cut it loading for two competition rifles plus farm ammunition all whilst working full time+ on a new business so I quickly changed to the Autotrickler moving from V2 to V3 and getting excellent results.

Fast forward to now and shooting has had to take a back seat due to business commitments and now having a couple of children but we still try to shoot the local pennants and every fox I see. So it was mostly out of curiosity that I purchased the SuperTrickler having been closely following its development. Now one thing the SuperTrickler does is make it really easy to calibrate the AnD FX series scales. Its arrival coincided with one of my business suppliers having an offer on 100 gram E2 quality calibration weights which are correct for milligram scales and I suddenly realised that I had no idea of the provenance of the 100gram weight that I had been using since I originally bought my scales so I made the purchase. Well, you guessed it… the old weight was nearly a full gram (906mg to be precise) lighter the certified weight now in my possession.

Kind of knowing what to expect, my next move was to grab a box of 55 grain projectiles and weigh a dozen of them with the old calibration and then reweigh them with the new and sure enough, with the old calibration the projectiles were all 0.5 grains heavier then with the new or more than enough to push me out of the node for my load data and potentially into some hot water with some of my Spicer Ftr loads, rendering years’ worth of data basically useless.

I conclusion, it’s obvious but your digital scales are only as accurate as the lump of metal you use to calibrate them! As always in shooting it’s the little, often simple things that will see you undone such as lose action screw costing you an OPM (sorry Sophie ) having just produced some of the best ammunition you can. And if you needed another reason not to blindly use someone else’s load even when using their barrel then here it is.

Have fun and shoot straight.

James.

PXL_20231022_210021734 by James Elphick, on Flickr

[Rich4]

Just a bush thought, why throw away "years of data" just continue using the original weight, therefore nothing changes.
There is nothing special about the exact weight until you are cross referencing with others, it is irrelevant to your charges.

[RDavies]

How right you are. A few years ago I started noticing all of my barrels started wanting heavier and heavier loads. Nothing too dramatic, maybe 1.5 to 1.8gn more over the last year or two. Penny dropped when 183 sierras started weighing less than 182gn. I dragged out my old balance beam scale and it confirmed my scale had started reading incorrectly. My scale is a bit of a weird one so I ended up having to take it to a scaleatrician (not sure of the accuracy of this name) to have it recalibrated. Now I have a few barrels to start fine tuning again, I think it is time to return to the scaleotromitist to show me again how to recalibrate it.

[Weairy]

This is a bit of a funny one. We use a set of eBay calibration weights which seem to be accurate enough. But if I calibrate the scales and build up a load using the scale, it shouldn't matter if it's measuring "accurately" or not, as long as it's measuring consistently. If "29gn" on those scales shoots, but it's really "29.24gn" true, it makes absolutely zero difference. It can measure in grains, grams, ounces or kwinkles for all I care, as long as the number says the same each time and it's consistently calibrated with the same check weight.

[RDavies]

This is a bit of a funny one. We use a set of eBay calibration weights which seem to be accurate enough. But if I calibrate the scales and build up a load using the scale, it shouldn't matter if it's measuring "accurately" or not, as long as it's measuring consistently. If "29gn" on those scales shoots, but it's really "29.24gn" true, it makes absolutely zero difference. It can measure in grains, grams, ounces or kwinkles for all I care, as long as the number says the same each time and it's consistently calibrated with the same check weight.

Very true if it stays at the same amount out and not switching back to using any other scales. I had issues when I switched over to some beam scales for doing load work out in the bush and again when I used someone else’s scales out at a big shoot and each time things went weird

[Rich4]

That is when standards become important, communication between scales

[bolster55]

The problem I have is the following,
I use a light cup on the scales which are then zeroed and powder put in to the required amount say 45 grns.
When removing the cup to put the powder into the case and looking at the reading on the the scales it is never the same but when placing the cup back on it reads zero????
Anyone else see this, or is it the scales?

[Rich4]

How much difference is there? If you’re talking a couple of hundredths of a grain air pressure will do it.
But providing it zeroes with the cup it’s probably ok? Try reweighing the same charge twice a few charges apart, consistency is more important than exact weight.

[bolster55]

I changed the cup to an aluminium one and appears to be ok!
Is it possible that the wood turned cup is drawing in moisture?

[Rich4]

Yes but not that quickly, more likely to be static electricity, I’ve designed and 3d printed a snail shell cup for the V4 and still don’t have one I’m happy with due to the difficulties of printing conductive filament with my printer and location

[Fire Dog]

Rich 4,
Get an aluminium cup from Area 419... Problem solved!
I have an auto trickler {Gen 2 with the full 419 up grade to get rid of all the printed plastic bits that came with it} Area 419 milled products are a vast improvement over the
original bits that come with the scale setup. Have also added the Ingenuity Precision trickler and that has really speeded up the weighing time with less over/under throws.
https://www.area419.com/product-categor ... cessories/