Check Weights

[beanieboy]

I wish to buy a couple of the above, 1,2,5,10 & 20grains in order to periodically check my beam scale. Prices listed are crazy for such a small item. Anyone know where I can get these at a sensible price?

[neutron619]

It's unlikely that you'll be able to. They are expensive precisely because they afford such a high degree of accuracy.

 

If I were you, I would reconsider whether the weights are actually any use. A beam scale is sufficiently accurate for reloading, but by their very nature, they aren't linear (i.e. a certain amount of adjustment does not always equal the same change in mass) which means you'll always have a degree of inaccuracy with any measurement, dependent on the settings on the beam and the actual weight being measured.

 

Furthermore, how do you plan to calibrate the scale? Placing a known 20 grain weight on a scale set up the same way every time will tell you that the mass of the weight hasn't changed since last time - but if it's an ordinary beam scale, what adjustment will you make when it comes out with a reading other than "20 grains" as it almost inevitably will?

 

Ok - so you could pull off the markings and stick them back on a bit further down the beam - or, if your scale has a container for adjustments, add or remove a piece of lead shot or some sand to get it reading exactly 20 grains with that weight on it - but after that, why do you need the weight? Do you expect the shot / sand to fall out of the adjustment container between uses and need replacing / re-calibrating? Either way, having made that adjustment, the non-linearity of the scale will probably mean that your readings for 1, 2, 5 and 10 grains will move elsewhere (and none of them by the same amount).

 

Maybe I'm missing something, or maybe you have a much more complicated, adjustable beam scale than the ones I've encountered, but it sounds like you haven't thought through whether you really need what I suspect you've been told by some know-it-all that you ought to have.

 

For a digital scale of course, it would be a different issue.

Edited March 29, 2017 by neutron619

[saddler]

Got a couple of the checkweights from the RCBS Chargemaster.

Can look them out, not sure what they're worth though.

[beanieboy]

It's unlikely that you'll be able to. They are expensive precisely because they afford such a high degree of accuracy.

 

If I were you, I would reconsider whether the weights are actually any use. A beam scale is sufficiently accurate for reloading, but by their very nature, they aren't linear (i.e. a certain amount of adjustment does not always equal the same change in mass) which means you'll always have a degree of inaccuracy with any measurement, dependent on the settings on the beam and the actual weight being measured.

 

Furthermore, how do you plan to calibrate the scale? Placing a known 20 grain weight on a scale set up the same way every time will tell you that the mass of the weight hasn't changed since last time - but if it's an ordinary beam scale, what adjustment will you make when it comes out with a reading other than "20 grains" as it almost inevitably will?

 

Ok - so you could pull off the markings and stick them back on a bit further down the beam - or, if your scale has a container for adjustments, add or remove a piece of lead shot or some sand to get it reading exactly 20 grains with that weight on it - but after that, why do you need the weight? Do you expect the shot / sand to fall out of the adjustment container between uses and need replacing / re-calibrating? Either way, having made that adjustment, the non-linearity of the scale will probably mean that your readings for 1, 2, 5 and 10 grains will move elsewhere (and none of them by the same amount).

 

Maybe I'm missing something, or maybe you have a much more complicated, adjustable beam scale than the ones I've encountered, but it sounds like you haven't thought through whether you really need what I suspect you've been told by some know-it-all that you ought to have.

 

For a digital scale of course, it would be a different issue.

 

I take your point, but I've always found the beam scales I've used to be very accurate. I just wish to carry out some sort of check to make sure they remain accurate. I tend to load down when it comes to recommended powder weight and can live with a small variance. The fact is there is no 100% when it comes to weighing....I could purchase a high end digital scale as a check, but if there are small variances, who's to say which scale is right? A small set of check weights is just one method of checking.

Got a couple of the checkweights from the RCBS Chargemaster.

Can look them out, not sure what they're worth though.

Let me know what you have saddler and perhaps we can agree a price.

[1066]

Personally I wouldn't be without a set of checkweights. A Lyman or RCBS set of grain weights is around £40, they will last a lifetime and not lose value.

 

Most reloading scales, if in good condition, tend to be fairly accurate in the 5-100 grain range, some do tail off toward the end of the range but usually only a couple of tenths of a grain. The problems begin when the scale isn't working as well as it should be and gives false readings.

 

A good beam scale will be accurate to 1/10th grain (4-5 kernels of Varget), some will consistently register a single kernel of Varget or similar.

 

I have seen many scales under/over read because of chipped knife edges, hairs of wire wool stuck to the magnets in the damper slot, poorly adjusted pan hanger stirrup etc.

 

How do you know your scale is still reading consistently without some means of checking them?

[neutron619]

How do you know your scale is still reading consistently without some means of checking them?

 

Aye, I agree. In fact, consistency is likely to be more important than absolute measure - but my points stand regardless.

 

Beam scales are not linear, ergo, they can't be calibrated - even if that's possible on a particular model - and they will not necessarily give a 20gr reading with a 20gr check weight at the same time as a 10gr reading with a 10gr check weight. You might have a useful area of linearity - you highlighted the 5-100gr range - but they can't be consistently accurate because the degree of movement of the needle over or under the mark at 500 grains represents, by definition, a mass 100 times greater than the same movement at 5 grains. Therefore, an equivalent resolution of adjustment isn't available at every given mass, which means even if the scale is - theoretically - perfect, the inability of a human to subdivide ever-tinier units of length to will render that perfect adjustment an impossibility.

 

You'd be far better off borrowing a 20gr check weight, or a 50gr one, since that will represent the mid-point of the adjustment resolution on a 500gr balance (assuming you discount anything below 5gr -> logarithmic units, etc. -> can't be bothered to write it all out -> ask me if it doesn't immediately make sense) and calibrating (by adding / removing sand, for example) against that, then giving it back and forgetting about it.

 

I'd wager there are almost no humans who can shoot well enough - I'm thinking rifles here - to notice the difference of a tenth of a grain of powder, even if every loading was measured to that accuracy. Other variables - case capacity, bullet imperfections, differences in lubricity of barrel inner surface area - will more than outweigh such extreme accuracy of powder or bullet weight. In shotgun shooting - well - forget it. We load by volume. The birds don't care.

 

Good luck, whatever you decide to do.

Edited March 29, 2017 by neutron619

[figgy]

Make your own from lead won't take long and you can have them for little or no money.

[Walker570]

Honestly, in the last 40yrs I have never bothered. I work up from 10% down on book until I get an accurate load. Load enough for twelve months of hunting. Load another batch and just check to see the groupings have not changed. Spend the money on powder and bullets.

[John_R]

I do use check weights, especially when I set my scales to weigh a different amount of powder from the last.

 

I use the RCBS set, and for example if I need 37 grains for a particular load, I place that amount of check weights in the pan, adjust to suit and that is correct for that weight. No worrying about linearity, as I took the time to set at that specific weight.

 

The next load I do might be 26 grains, or 42.5 and again I place that amount of check weights in the pan and off I go.

[neutron619]

I do use check weights, especially when I set my scales to weigh a different amount of powder from the last.

 

I use the RCBS set, and for example if I need 37 grains for a particular load, I place that amount of check weights in the pan, adjust to suit and that is correct for that weight. No worrying about linearity, as I took the time to set at that specific weight.

 

The next load I do might be 26 grains, or 42.5 and again I place that amount of check weights in the pan and off I go.

 

Now that approach makes sense. Expensive way of checking it, but it makes sense. I'd never stand up and argue that 37 grains and 37.1 grains are far enough apart for ordinary folk to tell the difference, but what you describe makes sense - takes the non-linear scales out of the equation, effectively, since you never refer to what they actually say.

Edited March 29, 2017 by neutron619

[1066]

I agree, a reloading scale can't be compared with an analytical balance but that's surely no reason not to regularly check it for accuracy and repeatability against a known standard. A lot of "measuring" that we do when trying to load an accurate round is actually comparing, making sure all our rounds are as consistent as possible, sometimes though, we do need to measure. When we do, it's nice to know your micrometer is telling the truth, checking it against a know standard slip gauge gives a certain amount of reassurance the bullet you are going to use to load your .303 is actually .311 and not a .308.

 

+/- A tenth of a grain when loading rifle rounds will, in general, not matter a jot but where do you draw the line, +/- a 1/5th? If I'm shooting my 6.5-284 at 1000 yds at the best part of £1 a bang, it's really no more effort to weigh the powder as accurately as possible. Just the same with concentricity, neck tension, trim length and all the other steps to a well prepped case.

 

My Pardini competition .32 centrefire pistol used a charge of 1.6 grains, my current .32 pistol uses 1 grain - really don't want to be 10% out with that.

 

Here's a reloading scale showing a fair degree of linearity:

 

https://www.youtube.com/edit?o=U&video_id=bVtYglAd9Dc

[Vince Green]

It doesn't matter anyway, you are only looking for consistency. You can weigh a series of metric nuts and bolts and use them as check weights.

 

Its more digital scales that need checking, beam scales don't alter

Edited March 30, 2017 by Vince Green

[Dougy]

I use a bullet that is close to the powder weight.

It's consistency that matters as has been said. 1 tenth of a grain is neither here nor there in the grand scheme of things when your weighing 25 or 55 grains.