Check weight for old Lyman M5

[MrBottleneck]

Can someone tell me what weight size the old Lyman M5 (made by Ohaus) scales came with that sat in the Leveling knob cup?
Are the new RCBS 10-10 check weights the same size weight?

Thanks

 

[dickn52]

Mine is marked 500GN

 

[jerseyjoe]

Mine is marked ACT.WT. 260.9 GN in smaller letters and 500 GN in larger.

It's to be used as a counterweight for measuring over 500 grains.

 

[Brians356]

It's not a "check weight", it's a counterweight, to extend the range of the scale by 500 grains when employed. And it should not be used as a check weight. Lyman (in their manuals) take pains to point out it does not weigh 500 grains, it is calibrated for use as a counterweight for the scale it was shipped with. Replacing a missing counterweight with another "500GN" counterweight probably won't work, unless someone can adjust it precisely to yield a +500-gr reading on your scale. And unless you need to weigh some 50 BMG bullets or something, I can't imagine most of us would ever need a 500-gr counterweight for a powder scale.
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[MrBottleneck]

It's not a "check weight", it's a counterweight, to extend the range of the scale by 500 grains when employed. And it should not be used as a check weight. Lyman (in their manuals) take pains to point out it does not weigh 500 grains, it is calibrated for use as a counterweight for the scale it was shipped with. Replacing a missing counterweight with another "500GN" counterweight probably won't work, unless someone can adjust it precisely to yield a +500-gr reading on your scale. And unless you need to weigh some 50 BMG bullets or something, I can't imagine most of us would ever need a 500-gr counterweight for a powder scale.
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Yep, I knew counter weight. I had a brain fart.
The 500 was what I was looking for.

 

[1066]

It's not a "check weight", it's a counterweight, to extend the range of the scale by 500 grains when employed. And it should not be used as a check weight. Lyman (in their manuals) take pains to point out it does not weigh 500 grains, it is calibrated for use as a counterweight for the scale it was shipped with. Replacing a missing counterweight with another "500GN" counterweight probably won't work, unless someone can adjust it precisely to yield a +500-gr reading on your scale. And unless you need to weigh some 50 BMG bullets or something, I can't imagine most of us would ever need a 500-gr counterweight for a powder scale.
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Why can't it be used as a check weight? It has its exact weight (260.9gn) stamped on it.

 

[hogan]

Ohause made the Lyman and RCBS scales. the rcbs counterweight will work in your Lyman

 

[Brians356]

Why can't it be used as a check weight? It has its exact weight (260.9gn) stamped on it.

If you find a 260.9gn check weight useful, by all means use it. But I'm not sure you can trust what's stamped on it since it wasn't intended to be used as an actual check weight.
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[1066]

You must be joking Brian... Of course it can be used as a check weight. It's made by Ohaus and has a stamp on it saying "this weight weighs 260.9 grains" My guess is that it actually weighs pretty close to 260.9gn.
If this weight is not exactly as stated then, when used as the attachment weight for weighing between 500-1000 grains it would be way out at the higher end.

Yes, it's nice to have a full set of grain check weights to check right through the range and especially around the range you intend to use. A set from RCBS/Lyman might cost $20-40, a certified lab set will cost many time that.

Set your scale to zero in the usual way. Now set your scale to weigh 260.9 and put the weight in the pan it again should read zero, or within a spit. This will immediately show up any gross error that needs further investigation.

This must be far more accurate than the usual "use a bullet/coin" type suggestions.

 

[Brians356]

My guess is that it actually weighs pretty close to 260.9gn.

I rest my case. "Close" is close enough for hand grenades and horseshoes.

But even assuming it is exactly 260.9 grs, it's only useful in pointing out an error in that weight range. Our scales are not perfectly linear in response across their total capacity range. I would think your time would be better spent using certified purpose-built check weights to zero your scale in the range where you do your weighing, say 20 - 60 grs (or narrower) for weighing our typical rifle powder charges.
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[dedogs]

But even assuming it is exactly 260.9 grs, it's only useful in pointing out an error in that weight range.

Scott Parker would disagree with you. He also does not use RCBS or Lyman check weights to verify the scales he works on. He found (as I have) that they are NOT accurate. dedogs

 

[Brians356]

Scott Parker would disagree with you.

You could be right, but he might prefer to speak for himself. I know I would.

As for the RCBS and Lyman check weights being untrustworthy, that wouldn't shock me, and may further caution against trusting the M5 "260.9" weight under discussion for a check weight. But I suppose I could be wrong.
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[dedogs]

But I suppose I could be wrong

You are. I'm also sure Scott won't mind me speaking for him as long as I don't pass on MIS-INFORMATION. dedogs

 

[dickn52]

ANY weight can be a check weight as long as you know how much the check weight weighs.

 

[Brians356]

ANY weight can be a check weight as long as you know how much the check weight weighs.

That's exactly right.
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[CharlieNC]

My 55.00gr checkweight was made by Hornady and certified on numerous units.

 

[xswanted]

My 260.9 gn weight weighs 260.9 on a digital hornady scale as well as a digital Dillon scale.

If I set my M5, which was made before I was born and works better than any new balance, at 260.9 the beam will read zero.

I've calibrated the M5 with it quite a few times and have not had a problem.

 

[expiper]

I like to use a Sierra bullet,,,,,Roger

 

[justinp61]

For the ranges of weight I weigh a 290 gr check weight wouldn't be what I'd want to check my scales with. Your mileage may vary though.

 

[1066]

My 260.9 gn weight weighs 260.9 on a digital hornady scale as well as a digital Dillon scale.

If I set my M5, which was made before I was born and works better than any new balance, at 260.9 the beam will read zero.

I've calibrated the M5 with it quite a few times and have not had a problem.

I have three M5's currently on hand - I've just weighed all the weights on my digital Ohaus lab scale. Two weigh 260.9 one weighs 260.92..

I work on a fair few scales - If a scale zero's reliably at "0" and reads within a 10th grain at 260.9 when weighing the auxiliary weight, there's not much wrong with the scale. It will read within a 10th or so right through the range.

Yes, there may be minor mechanical damage to the beam, may be a burr stopping the main poise locating correctly down in the notch etc. so it's always worth using check weights close to the weight you are using. Of course, it's much more important for the scale repeat reliably, the fact that it's a 10th over or under isn't much of a problem as long as it's always the same.