BB Variation

[Sewdhull]

So just out of interest I asked a lab friend of mine to measure the weight some of the BBs I have, all Vorsk ones.

 

Here's his summary.

 

Weight       .43g     .4g       .32g

 

Mean         0.424   0.404  0.324

SD              0.002   0.004  0.001

RSD            0.5%     0.9%    0.5%

Median      0.424    0.403  0.324

 

The BBs were measured, 10 of each from a bottle,  to 4 decimal places.

 

Mean is the commonly called average, SD the standard deviation, RSD is the relative standard deviation around the mean, and median is the middle value of the dataset.

 

The .32s had a max and   min difference over the 10 samples of .005g, which is just 1.6%. Pretty good I reckon.

[hunter511]

Vorsk being Vorsk Id be more interested in how many are spherical as opposed to cuboidal and size measurements.

[Sewdhull]

Well I would suggest if they are getting the weight right they are half way there at least. Perhaps I'll see if my lab buddy can look through a scope at a couple. I'm unsure how you would measure sphericity... Do you?

[Rogerborg]

1 hour ago, hunter511 said:

Vorsk being Vorsk Id be more interested in how many are spherical as opposed to cuboidal and size measurements.

 

2 minutes ago, Sewdhull said:

I'm unsure how you would measure sphericity

 

I'll be running Vorsk 0.28g in a 6.00m barrel on Sunday, I'll let you know how long before I get a solid plastic cored barrel.

[Leo Greer]

On 31/05/2024 at 20:11, Sewdhull said:

Well I would suggest if they are getting the weight right they are half way there at least. Perhaps I'll see if my lab buddy can look through a scope at a couple. I'm unsure how you would measure sphericity... Do you?

Bootleg method: micrometer. Turn the BB and keep measuring.

[Lozart]

On 31/05/2024 at 17:35, Sewdhull said:

So just out of interest I asked a lab friend of mine to measure the weight some of the BBs I have, all Vorsk ones.

 

Here's his summary.

 

Weight       .43g     .4g       .32g

 

Mean         0.424   0.404  0.324

SD              0.002   0.004  0.001

RSD            0.5%     0.9%    0.5%

Median      0.424    0.403  0.324

 

The BBs were measured, 10 of each from a bottle,  to 4 decimal places.

 

Mean is the commonly called average, SD the standard deviation, RSD is the relative standard deviation around the mean, and median is the middle value of the dataset.

 

The .32s had a max and   min difference over the 10 samples of .005g, which is just 1.6%. Pretty good I reckon.

 

Encouraging for sure. I do wonder though if 10 of each is a fair sample but to be statistically significant you'd have to test way more from more batches than a favour from a friend would allow.

That said, I've not had any issues with Vorsk ammo that I've used in the past. Be interesting to see who OEMs it.

[Sewdhull]

1 hour ago, Lozart said:

 

Encouraging for sure. I do wonder though if 10 of each is a fair sample but to be statistically significant you'd have to test way more from more batches than a favour from a friend would allow.

That said, I've not had any issues with Vorsk ammo that I've used in the past. Be interesting to see who OEMs it.

Yeah you'd need a hundred samples for any statistical meaning, he just chose 10 from 500 or 2000. For roundness you'd probably want to rotate them and try to detect any wobble, on a stream of air perhaps, like you do when you're getting Maltesers by floating them over your mouth and blowing the air out... what, just me?

[Rogerborg]

On 31/05/2024 at 19:16, Rogerborg said:

I'll be running Vorsk 0.28g in a 6.00m barrel on Sunday, I'll let you know how long before I get a solid plastic cored barrel.

 

Surprisingly, I didn't get any jams, and it's a proper titeboi that BBs will only just barely roll down without assistance.  Seems that even "Vorsk" Nuprol can source round BBs.

[Pseudotectonic]

How was the weighing done? I mean are they certain the accuracy of the scale is within ± 0.001 g?

 

Also sample size = 30 is often used as rule of thumb for statistics, it's usually good enough to locate your normal distribution i.e. central limit theorem

[Sewdhull]

It's a science lab populated by research scientists with PhDs.

They have proper calibrated kit so yes the weighing is likely accurate.

46 minutes ago, Rogerborg said:

 

Surprisingly, I didn't get any jams, and it's a proper titeboi that BBs will only just barely roll down without assistance.  Seems that even "Vorsk" Nuprol can source round BBs.

I'd suggest getting the bbs  round goes hand in hand with the rights weight( ie the right amount of material)

I'm pleased those bbs were satisfactory