Highly accurate scales

[John MH]

I am using an RCBS 502, and it does not return precisely to the same point. I.e. if I zero it, and then tap it gently, it will not settle back, every time, to precise zero. It is within its .1 gr, but not absolutely dead on.

It needs tuning then.

[Mr_Logic]

OK, how do I go about doing that?

[John MH]

Either send them to Scott Parker in the USA or PM 1066 on here who may be able to help.

[Alpha1]

Have a word with 1066 on here you would be better off buying a tuned beam scale from him or get him to tune yours and get one of his target master tricklers. That's the set up I use.

[rox]

Denver Instruments MXX 123 scale weighs to one fiftieth of a grain. Company near York - Pocklington I think - imports them. Check on Ebay. About £250

I'm always surprised when Vince recommends this balance. The 123 may be 'readable' to 0.02 grains, but that's a very different thing from being 'accurate' to that resolution. Maybe it just goes to show that we really don't need the charge weight accuracy that we think we need. It seems to be generally accepted that milligram weighing is beyond (or at least at the very limits of) the technical capabilities of strain gauge load cells as used in the MXX-123 and the other similar rebadged/repackaged models (VIC-123, Sartorius AY-123 etc). This is probably why there are so many negative reports related to the poor linearity, drift, repeatability, stability and speed - see below for a few quotes that came up in just a few seconds of searching. Some may be due to measuring technique or environment (which needs to be carefully controlled to achieve good measurements with any balance at this resolution) but the weight of negative comments is quite overwhelming. IIRC, when Laurie Holland tested the balance for Target Shooter mag he found that it required zeroing for every charge measurement, suggesting that drifted so much and so quickly that it was out by the time a single measurement had been made.

Repeatable and reliable milligram weighing is much better served by a minimum of a 'magnetic force restoration' load cell, which also usually results in faster settling and being less susceptible to temperature variations etc. These start at about £500 or so. I have a pair of A&D FX-120i balances, which are entry-level units for milligram weighing. They are quite tough and durable, and often sold for schools and college labs etc making them pretty suitable for the reloading bench. Even then, they require good environmental conditions, careful measuring technique and plenty of warmup otherwise I observe a little drift over a few hours – you can expect to pay closer to £1000 for really good quality milligram balances that are rock solid. Don't forget that many balances have a degree of zero tracking, so observing drift at/from zero is not necessarily a good indication of real stability.

If you do decide to go with a 123 balance bear in mind that there are plenty of reports of bad examples and early failures, so I definitely wouldn't buy one on eBay.

Here are some comments from reviews and users:

http://bulletin.accurateshooter.com/tag/mxx-123/
"serious shortcomings when used to weigh powder"

http://forum.accurateshooter.com/index. ... =821075.15
"I have suffered with the same drifting issues,etc. regarding the Denver MX 123 scale and finally gave up in disgust!"

"I gave up on mine a couple of years ago. It drifted when powder was being weighed even after being turned on for days. Money down a hole."

"I just wanted to report that my MXX-123 has turned out to be pretty much junk."


..

[Gun Pimp]

Denver Instruments MXX 123 scale weighs to one fiftieth of a grain. Company near York - Pocklington I think - imports them. Check on Ebay. About £250

I'm always surprised when Vince recommends this balance. The 123 may be 'readable' to 0.02 grains, but that's a very different thing from being 'accurate' to that resolution. Maybe it just goes to show that we really don't need the charge weight accuracy that we think we need. It seems to be generally accepted that milligram weighing is beyond (or at least at the very limits of) the technical capabilities of strain gauge load cells as used in the MXX-123 and the other similar rebadged/repackaged models (VIC-123, Sartorius AY-123 etc). This is probably why there are so many negative reports related to the poor linearity, drift, repeatability, stability and speed - see below for a few quotes that came up in just a few seconds of searching. Some may be due to measuring technique or environment (which needs to be carefully controlled to achieve good measurements with any balance at this resolution) but the weight of negative comments is quite overwhelming. IIRC, when Laurie Holland tested the balance for Target Shooter mag he found that it required zeroing for every charge measurement, suggesting that drifted so much and so quickly that it was out by the time a single measurement had been made.

Repeatable and reliable milligram weighing is much better served by a minimum of a 'magnetic force restoration' load cell, which also usually results in faster settling and being less susceptible to temperature variations etc. These start at about £500 or so. I have a pair of A&D FX-120i balances, which are entry-level units for milligram weighing. They are quite tough and durable, and often sold for schools and college labs etc making them pretty suitable for the reloading bench. Even then, they require good environmental conditions, careful measuring technique and plenty of warmup otherwise I observe a little drift over a few hours – you can expect to pay closer to £1000 for really good quality milligram balances that are rock solid. Don't forget that many balances have a degree of zero tracking, so observing drift at/from zero is not necessarily a good indication of real stability.

If you do decide to go with a 123 balance bear in mind that there are plenty of reports of bad examples and early failures, so I definitely wouldn't buy one on eBay.

Here are some comments from reviews and users:

http://bulletin.accurateshooter.com/tag/mxx-123/
"serious shortcomings when used to weigh powder"

http://forum.accurateshooter.com/index. ... =821075.15
"I have suffered with the same drifting issues,etc. regarding the Denver MX 123 scale and finally gave up in disgust!"

"I gave up on mine a couple of years ago. It drifted when powder was being weighed even after being turned on for days. Money down a hole."

"I just wanted to report that my MXX-123 has turned out to be pretty much junk."


..

I never switch off my Denvers.

A few complain about 'drifting' but, if you read the blurb. the correct weight is shown in the first three seconds of dumping the powder. Mine work great - what more can I say.

I actually do all my weighing on an RCBS Chargemaster - F Class, Tactical, McQueen, Military etc. It's very good but, for 600 and 1000 yard benchrest, I dump the RCBS charge on the Denvers for a second opinion - and adjust if more than 0.02grains either side of my chosen weight.

Works for me.

Vince

[ovenpaa]

Vince, typically how far out will the Chargemaster out for you and have you ever measured how much impact the error has on vertical dispersion?

[Gun Pimp]

Vince, typically how far out will the Chargemaster out for you and have you ever measured how much impact the error has on vertical dispersion?

Good Question!

For short range benchrest, we load on the point and throw our charges - my Harrel (powder thrower) is accurate to 0.3 grains - this has no 'vertical' effect at 100 yds. At 200, I prefer to weigh - using the Chargemaster - probably to within 0.1 gn. though many top shooters still rely on their Harrels.

What effect one-tenth of a grain would make at 1000 yards is the age-old conundrum! To be honest - conditions in this country are rarely - if ever- good enough to even try and evaluate this. If you want results at 1000 yds - you do the very best you can - with everything!

Last weekend at our 1000 yard BR shoot, one guy shot a 3.765 inch group and his next group, shot a couple of minutes later in seemingly identical conditions, measured 14.449 inches. Go figure - as the Yanks say.

Many F Class Open shooters are operating at benchrest standards - with gun and reloading techniques and achieving stunning results.

Incidentally - on the subject of wandering zeros - there is a little piece on Accurate Shooter at the moment - www.6mmBR.com

Vince

[Blu]

I have both the RCBS Chargemaster and the 505 scales. I have got the charge master to drop from 0.1 grn up to a Grn then weighed the powder on the 505 and the chargemaster has been spot on every time. The thing I like about the chargemaster is no waiting for it to warm up and it is damned accurate, having tried a few others in the past and seen others being used, IMO I still reckon the chargemaster is the best one out there and it's still going strong after four years of heavy usage.

Blu

[rox]

Vince, typically how far out will the Chargemaster out for you

Good Question!

That is a good question. When I found for the answer under lab conditions I was extremely surprised! I couldn't tell you what it looks like from the perspective of a dodgy xxx-123 balance though :)

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