Arian2020

Thank you very much Arian2020 ! Appreciate all the efforts and time to resolve this mystery 😀.
So here what I understand from all the measurements you posted above:
Outside edge thickness:
2017:  25 coins x 3.07mm each = 76.75mm
2024: 25 coins x 2.91mm each = 72.75mm
Difference is: 4mm (which is about an additional 1.3 coin).
That makes since now that the 2017 stack is taller than the 2024 stack! We only need to confirm with anyone else who has 2017 Britannia if their edge thickness is 3.07mm too.

More photos…Outside edge thickness 2017, 2021, 2024

Hello everyone! 😬 Apologies for the delay; you won’t believe how much I struggled to get  an LR44 battery for my callipers! 🙄
Anyway, re-did the stacking and tested measurements (Width and thickness) and the results are…inconclusive? 
 
Please see photos attached: the 2017 stack of 25x Britannias is still 1 whole coin to 1 1/2 coins taller than the 2024 stack, while the 2021 stack is somewhere in-between. The thickness of the 2021 coin, however, is 0.01 mm taller than the 2024 stack so you’d think overall that stack would be slightly taller (but this could be due to user error 😋). What does look likely, however is that the 2024 coins have a height of 0.03/0.04mm less than the other coins and counted up over 25x will result in a stack 0.75-1mm shorter than the others, which does seem not to be the case at the 2017 stack is at least 3mm taller than the 2024! 🤷🏽‍♂️ 
Anyway, anybody else want to play Scrooge McDuck and measure the size of your stacks, please be my guest and tell us if they are within the tolerance(s)?
 

More photos…Outside edge thickness 2017, 2021, 2024

More photos…Inside thickness 2017, 2021, 2024
 
 
 

More photos…Width 2017, 2021, 2024
 

Hello everyone! 😬 Apologies for the delay; you won’t believe how much I struggled to get  an LR44 battery for my callipers! 🙄
Anyway, re-did the stacking and tested measurements (Width and thickness) and the results are…inconclusive? 
 
Please see photos attached: the 2017 stack of 25x Britannias is still 1 whole coin to 1 1/2 coins taller than the 2024 stack, while the 2021 stack is somewhere in-between. The thickness of the 2021 coin, however, is 0.01 mm taller than the 2024 stack so you’d think overall that stack would be slightly taller (but this could be due to user error 😋). What does look likely, however is that the 2024 coins have a height of 0.03/0.04mm less than the other coins and counted up over 25x will result in a stack 0.75-1mm shorter than the others, which does seem not to be the case at the 2017 stack is at least 3mm taller than the 2024! 🤷🏽‍♂️ 
Anyway, anybody else want to play Scrooge McDuck and measure the size of your stacks, please be my guest and tell us if they are within the tolerance(s)?
 

More photos…Outside edge thickness 2017, 2021, 2024

More photos…Outside edge thickness 2017, 2021, 2024

More photos…Inside thickness 2017, 2021, 2024
 
 
 

More photos…Width 2017, 2021, 2024
 

Hello everyone! 😬 Apologies for the delay; you won’t believe how much I struggled to get  an LR44 battery for my callipers! 🙄
Anyway, re-did the stacking and tested measurements (Width and thickness) and the results are…inconclusive? 
 
Please see photos attached: the 2017 stack of 25x Britannias is still 1 whole coin to 1 1/2 coins taller than the 2024 stack, while the 2021 stack is somewhere in-between. The thickness of the 2021 coin, however, is 0.01 mm taller than the 2024 stack so you’d think overall that stack would be slightly taller (but this could be due to user error 😋). What does look likely, however is that the 2024 coins have a height of 0.03/0.04mm less than the other coins and counted up over 25x will result in a stack 0.75-1mm shorter than the others, which does seem not to be the case at the 2017 stack is at least 3mm taller than the 2024! 🤷🏽‍♂️ 
Anyway, anybody else want to play Scrooge McDuck and measure the size of your stacks, please be my guest and tell us if they are within the tolerance(s)?
 

Hi everyone,
Just testing some recently purchased tubes of silver Britainnias and they all pass the weight test (31.19g-31.25g), pass the 99.9% purity test on the Sigma PMV and pass the magnet test and the width check (as they all fit into regular Britannia tubes and the STEALTH laser-cut MDF card). However, when having a stack of 25x 2017, 2021 and 2024 next to each other, the 2017 seems to be taller by as much as a whole coin, with the 2021 coming next and the 2024 the shortest. Any idea why these 2017 ones seem thicker? Raised rims? Any ideas would be much appreciated😶‍🌫️

Sorry everyoneI, have not had the time to do the checks yet (between work and play) - I’ll see if I can get to it over the next week or so 📐

Sorry everyoneI, have not had the time to do the checks yet (between work and play) - I’ll see if I can get to it over the next week or so 📐

Sorry everyoneI, have not had the time to do the checks yet (between work and play) - I’ll see if I can get to it over the next week or so 📐

I have some lovely Mitutoyo digital Vernier callipers, if you'd like to send me your samples. I can't guarantee you'll get the samples back though

I know I’m late to the game on this one, but I have experienced this same thing with various Canadian Maple Leaf coins as well. Some years stack slightly higher. DNA (2014+) seem to have a minuscule height difference. If you trust the place you got them from and they pass the various tests you put them through, you should be good. 

@Arian2020: Any update? 🙂

Yeah good idea - I do have a set somewhere that I will dig out and measuring them on a known flat surface (rather than the green felt) seems like a logical step. Thanks again for the input 😎👍🏽

Yeah good idea - I do have a set somewhere that I will dig out and measuring them on a known flat surface (rather than the green felt) seems like a logical step. Thanks again for the input 😎👍🏽

Thank you stackerp5 - it is interesting to note all these differences and I am thankful to hear that others have also seen these types of discrepancies 👍🏽 

Thank you James, weird though - slight panic when you test them and when compared side-by-side you can just about tell the 2017 seem slightly thicker than the 2024 🤷🏽‍♂️

Hi everyone,
Just testing some recently purchased tubes of silver Britainnias and they all pass the weight test (31.19g-31.25g), pass the 99.9% purity test on the Sigma PMV and pass the magnet test and the width check (as they all fit into regular Britannia tubes and the STEALTH laser-cut MDF card). However, when having a stack of 25x 2017, 2021 and 2024 next to each other, the 2017 seems to be taller by as much as a whole coin, with the 2021 coming next and the 2024 the shortest. Any idea why these 2017 ones seem thicker? Raised rims? Any ideas would be much appreciated😶‍🌫️

Hi Pete, thank you that sounds very plausible too - at first I thought I was missing one from the stack and literally counted them 5x over! 🤪