Where do I find check weights reasonably priced?

[mr.steve]

I recently bought a digital scale that doesn't include a calibration weight. I got this scale because of the big easy to read display. The instructions call for a 200 gram weight to calibrate. Of course I looked on line and found weights available but the prices are high. The scale has a resolution of 0.01 grams which equals 0.154 grains. I suppose my question is about the tolerance of error. I'm considering ASTM 4 or OIML F2. Am I thinking this right?

 

[miguel]

So, do you want to measure in grains or grams?

I have been wanting to get some check weights and it looks like Midwayusa.com has some good sets from RCBS and Lyman. They range from $30 - $60 once you figure in shipping.

Would love to find a local source, but haven't yet.

 

[mr.steve]

Miguel, The scale is calibrated using a 200 gram weight. My practical usage will be in grains. Some of the sets I see available do not contain a 200 gram weight .

 

[Mech45]

[ame="http://www.amazon.com/American-Weigh-Scales-Calibration-Weight/dp/B0051OHKXU"]Amazon.com: American Weigh Scales 500 Gram Calibration Weight + 200 Gram Calibration Weight + 100 Gram Calibration Weight + 50 Gram Calibration Weight: Office Products[/ame]

These are OIML Class: M2

HTH Chris

 

[slackerisme]

Why not just find a "thingamajig" that weighs 200 grams on more than one scale and use that. I understand that it could potentially be inaccurate, but what method would you use to verify the purchased unit?

 

[Broom_jm]

I applaud your dedication to precision, knowing you are relatively new to reloading and want to make sure your scale is accurate. I would contact the manufacturer of said scale and inquire as to the availability and cost of a check weight from them. Odds are VERY good you'll have one in the mail, for free, before the day is over.

The other thing you can do, if you have commercially produced, jacketed bullets, is weigh 10 or 20 of them, and take an average. If your scale agrees with the number printed on the box, within about two tenths of a grain, then you are good to go.

I have done this little experiment several times, for a variety of reasons. All I can say is quality control must be very good at bullet manufacturers these days, because their bullets are so close to exact...well, you could almost use 'em for check weights!

 

[billybob44]

Broom is Right On..(AGAIN!!)

I applaud your dedication to precision, knowing you are relatively new to reloading and want to make sure your scale is accurate. I would contact the manufacturer of said scale and inquire as to the availability and cost of a check weight from them. Odds are VERY good you'll have one in the mail, for free, before the day is over.

The other thing you can do, if you have commercially produced, jacketed bullets, is weigh 10 or 20 of them, and take an average. If your scale agrees with the number printed on the box, within about two tenths of a grain, then you are good to go.

I have done this little experiment several times, for a variety of reasons. All I can say is quality control must be very good at bullet manufacturers these days, because their bullets are so close to exact...well, you could almost use 'em for check weights!

^^^+1 For Broom...I have been using Sierra Bullets for this for years. You wll find Sierra Bullets (At least .224" diameter-50-55gr.) are all within .01gr. of "Box Tab" reading. Thats been my case anyway...Bill.

 

[mr.steve]

Thanks for the ideas. I am unsure of how accurate the test weight needs to be. for example, if I'm loading close to the maximum load, let's say 0.3g shy of the max how much error can I tolerate safely? Here's a table of classes for calibration weights:

 

[Broom_jm]

Since your scale, itself, is rated to be accurate to within +/- .15 grains, I should think a check weight meeting, or exceeding that standard, would suffice. M1 or #4 ?

To be honest, you're probably over-thinking this...contact the maker and get a check weight. It will be accurate enough. The truth of the matter is that reloading scales need to be very consistent, over a number of charges, not extremely precise for each individual charge.

There is a sliding scale of weight and volume that mitigates the perceived danger of a charge that is one or two tenths over max. It is one thing to be cautious and prudent, another to be obsessive and paranoid.

 

[mr.steve]

thank you Jason, I am probably over thinking the matter. As noted I'm new to reloading. I am not so much obsessive, I just try to be thorough. #4 was my first choice. Your reply helps me establish a reasonable starting point. My education continues...

 

[Broom_jm]

Well, Steve...over-thinking something is WAY better than the alternative!

 

[miguel]

Well, Steve...over-thinking something is WAY better than the alternative!

I resemble that remark!