Digital or beam scale comparison

[Swarovski1]

I am just curious to how accurate they are and how them compare.

Can some of you enter scales. weigh 1/10 of a grain of H 4350 and count the kernels to see how it varies.

[duey]

Counting kernels in my thinking won't work due to variance of density and size from kernel to kernel will differ

Perhaps weighing 1/10 of a grain of powder, or preferable 1 grain, on one scale then transferred that weighed powder to second scale and see if the weight corresponds to the same indicated weight

[1066]

Here's a set of beam scales weighing to single kernels of Varget powder:

 

.https://www.youtube.com/watch?v=dnVOoGd1bDU

[Brillo]

My Redding beam scales, thanks to a certain gent on here, registers on kernel of N140. This appeals to my reloading OCD but in truth the variance in windage and bullet drop of that kernel is debatable.

[gbal]

OK,Neil-an interesting question.Opinion will vary.Really good testing will be rarer.Let's leave aside questions about what "accuracy' means in weighing,meanwhile (because it may/not matter much,but acept that 'reliability'-same object when on the scale pan,es the same weight (+/_ tolerance,of course)>

 

Since I was playing with a manual (Redding) trickler anyhow,here are some findings for a RCBS/Ohaus 5-10 scale,tuned by TM (its used,and not recent and isn't therfore a special one-but seems just like his video):

So is it any good-it's very good.

 

I took Vihtavuori's load data for V 140 for 155 Sierra 308 :the min is 39.2 grains giving 2431 fps and 44.1 g giving 2680fps.

 

So we can take it that 4.9 g of V140 gives 249 fps -or more helpfully .1grain gives 5fps in the load area we are interested in.

 

Preliminaries:

I added as many kernels as it took to increase the scale weight reading by .1g (trial and error).It was on average 5 (they are either not all the same,or discrimination by the scales is reliably about 1-2 kernels(as per 1066s video)

 

OK,now for the real testing:of a grain....

 

I weighed out 45 g according to the scales. I removed the pan/powder and replaced it,checked reading,and did so 5-10 times-it was reliable to a +/- of a couple of kernels...say 5

 

That I take to mean at the indicated 45g,there would be a reliability of 5 kernels,which (see above) is ,as is claimed, .1g

 

 

Fine/good. Does it matter?

Well,the direct relevance of powder is that it gives velocity-and see above- .1g of V140,in this zone of loading for a 155 Sierrra 308,means 5fps.

So,I think,the beam scale is reliably measuring this powder to 5fps. Seems good to me.

 

How good: well,let's do a WEZ analysis:

 

Assume high confidence wind /range are assessed to 1% accuracy,the rig's precision is .5 moa,and let us see what happens at 1000y,with SD in velocity of 20,15,10 fps: here are the hit %s on 5" gongs:7%,9%,and 13% respectively ie with 5 fps fromthe beam,hit % will be around 15%.

 

But that is only 2% improvement improvement from the 13% that twice the SD (13% with 10 fps).

 

Well,it all helps,but seems that .1g is pretty good.....there are far more heavy conibutors to missing.

 

AND,I suspect electronic scales will generally be as good,with little scope for improved weighing that will impact much more accurately on target....

 

It's all worth having,but seems unlikely that there will be a significant advantage either way.

And any advantage will be considerably less at shorter distances.

 

A tuned beamscale weighs out powder to an accuracy better than.1grain,and that translates to a fps variation of 5fps,and that scarcely matters given the raft of variables.

 

Shooter confidence of course is not measureable,even if its effects might be broady though positive.

I did not measure kernels precisely,especially the small hole up the centre,but I think we can ignore this here. :-)

 

And another wet pm is filled in.....

 

gbal

[Brillo]

Great answer George. It reminded me of my 6 Sigma days and all the different confidence tests. Oh how I miss them.....

[Swarovski1]

I read on accurate shooter 3 kernals is about 0.1grs depending on kernal size.it seems 0.1 of a grain is as accurate as it gets.they probaly don't make a scale that's perfect.what you need is consistantcy.recently I pulled a 6.5x47 load and everytime I weighed it it weighed different.well 3 times was different.we are talking minute differences.

[gunner]

I know a member who accidentally poured wrong powder into wrong tub , it was a hard to find powder and he spent 2 days with tweezers picking the slightly different kernels appart ! I wouldn't of even thought about it !

[Swarovski1]

Only one tub of powder on my bench at a time.once finished with it all goes away before I start on something else.