reloading scale question

[sam77757]

how accurate does a set of scales need to be? i have seen them offered for sale having a tolerance of 0.5 and another brands tolerance of 0.2 and the 0.2 is the lowest tolerance i have seen! from what i have seen the 0.2 can be bad on some loads any ideas?

 

[mattsbox99]

You mean resolution, not tolerance.

You want a resolution of .1 grain.

I have a PACT 1500 grain capacity digital scale that is accurate to .1 grain and has a resolution of .1 grain.

http://pact.com/index.php?option=com_co ... &Itemid=31

The RCBS 750 and 1500 scales are both built by PACT.

 

[sam77757]

instead of tolerence i was meaning accuracy as in how accurate they need to be ! so a 0.1 +/- grain is ok? so really how do you know exactly whats being loaded is my question (if im loading 8.1 gr and the scales read 8.1 it could actually be 8.0 or 8.2 is that really exceptable?

 

[Sgt Garcia]

instead of tolerence i was meaning accuracy as in how accurate they need to be ! so a 0.1 +/- grain is ok? so really how do you know exactly whats being loaded is my question (if im loading 8.1 gr and the scales read 8.1 it could actually be 8.0 or 8.2 is that really exceptable?

No, it would not actually be "8.0 or 8.2". It could be 8.05 to 8.15 or .1 grain.

The correct term is resolution as stated.

I'm not sure what you mean by "bad" but if .2 grain put you beyond a safe threshold the load is already too hot IMO.

Dennis.

 

[redhawker]

The scale may be accurate to 0.1 but I believe that means as compared to other scales. My scale might show 8.0 grains as 8.1, your scale may show 8.0 grains as 7.9 grains. The thing is if my scale shows 8.0 grains as 8.1 it will show 8.0 grains as 8.1 every time. As long as you work up a load properly and you use the same scale every time you should be safe. What I'm saying is if my scale is showing 8.0 as 8.1, but if that's a safe and accurate load, my scale will show it as 8.1 every time so you will get a consistent load. Your scale won't show 8.0 and one load will be 7.9 then the next be 8.1 then the next be 8.0. (If I didn't make that sound too confusing)

 

[sam77757]

The scale may be accurate to 0.1 but I believe that means as compared to other scales. My scale might show 8.0 grains as 8.1, your scale may show 8.0 grains as 7.9 grains. The thing is if my scale shows 8.0 grains as 8.1 it will show 8.0 grains as 8.1 every time. As long as you work up a load properly and you use the same scale every time you should be safe. What I'm saying is if my scale is showing 8.0 as 8.1, but if that's a safe and accurate load, my scale will show it as 8.1 every time so you will get a consistent load. Your scale won't show 8.0 and one load will be 7.9 then the next be 8.1 then the next be 8.0. (If I didn't make that sound too confusing)

so how do you know your scales are showing 8.0 as 8.1 ? if your scales are showing 8.0 couldnt it actually be 7.9 since the "resolution" is +/-? or better yet if my scales are showing 8.0 how do I know if its 7.9 or 8.1 if my scales have a .2 +/-

2nd
if your working a load that shoots great at lets say 65.5 gr and your actually loading them 65.6 or 65.4 there could be a big difference IE (BAD) accuracy "I'm not sure what you mean by "bad" but if .2 grain put you beyond a safe threshold the load is already too hot IMO. " .2 grain can change the accuracy am i right?

"(If I didn't make that sound too confusing)"

i have been confused way before your explination HAHA

 

[427mach1]

so how do you know your scales are showing 8.0 as 8.1

The scale manufacturers sell "check weights" that you might consider. See http://www.midwayusa.com/viewproduct/?p ... ber=493216

They don't say what the weight tolerance is, however, so I'm not sure if this will answer your question.

Keep in mind that maximum loads are determined by the manufacturer (Hornady, Speer, Hodgdon, etc) for a particular gun and may or may not be safe in your gun. That is why they tell you to approach maximum loadings with great caution. If you determine that 65.5 grains (according to your scale) is safe in your gun and that it doesn't show signs of excessive pressure, then it doesn't matter if it actually was 65.4, 65.5, or 65.6. If you are concerned about it, then drop down a few tenths of a grain to give yourself some margin of safety. I doubt if a few tenths of a grain will greatly affect accuracy but there is only one way to find out for your application.... Go shoot it! Look at it as another "excuse" to go to the range!

 

[Sgt Garcia]

Sam,

Consider this........bench rest match shooters, where accuracy is everything, don’t even weigh their charges after they have a load worked up. You are making too much out .2 grain.

Having said that, if I was to use a digital scale, and I do, I would want it to be accurate to .1 grain.
The way you know it’s accurate is by checking it with the usually provided test weight. I wouldn’t use a digital powder scale without having weights to verify its accuracy.

Dennis.

 

[Sgt Garcia]

The scale may be accurate to 0.1 but I believe that means as compared to other scales.

Actually that means compared to a known standard or test weight not to other scales.

Dennis.

 

[sam77757]

Sam,

Consider this........bench rest match shooters, where accuracy is everything, don’t even weigh their charges after they have a load worked up. You are making too much out .2 grain.



Dennis.

im sure they have alot better equipment that i use !! and since i just started reloading i weigh each charge 1 at a time and was just wondering about how accurate my scales need to be. so as far as the "you are making too much out of .2 grains " i would respond with a (YOU BET YOUR A$$ im going to make a big deal out of it ) atleast till i get a few thousand rounds under me and get it all figured out! but thanks agian for all the info ..

 

[Jimbo357mag]

I don't know all the technical terms but there are other things to consider when using a scale besides resolution I believe there is sensitivity or what happens when you add a few grains of powder? Does it always increase as it should or does the scale "stick", also repeatability, if you take the weight off the scale and then put it back on does it return to where it was before? and finally "zero" and drift, does the empty scale always return to zero?

When reading gauges or instruments you sometimes tap them to get a true reading. Anything mechanical can hang-up. With my digital scale I will often take the powder cup off, let the scale zero and then put the powder back on to make sure of the weight, essentially weighing the charge twice. When using a balance beam scale I will tap the scale and make sure the pointer swings the same amount on either side of the mark before settling. Those techniques were the way I was taught to read instruments.

...Jimbo

 

[Sgt Garcia]

All good points Jimbo......

Dennis.

 

[WESHOOT2]

I 'zero' my scale each and every time with a Lyman Scale Weight Check Set.

 

[Ruber]

I 'zero' my scale each and every time with a Lyman Scale Weight Check Set.

+1 and Jimbo had a good post too!

Also, if the precision of 0.1gr is not adequate for what you want when/if you start using a powder measure (and checking say every 10 or so loads), you can always throw two loads and weigh them together, effectively obtaining a precision of 0.05gr when you setup/check your measure. You need to make sure your methods with the powder measure are consistent enough to have this make a real difference.

This is quick and easy enough that I'll do this with even plinking loads as it can also minimize some of the artifacts that Jimbo mentioned.