Chargemaster 1500 accuracy

[PhilC]

Years ago I ordered a small brass insert from ebay, which worked better than the straw for me.

I got a brass insert too, don't recall if from same source or elswhere works very well.

 

[ebb]

I've been using a 1500 since about a year after they came out and was pleased with it until about a year and a half ago. I found that some throws were off a lot. Asked here and found the biggest issue is static electricity. RCBS says to wipe with dryer sheet or antistatic cloth every time you use it. What have you guys done about static elec.? I bought a little kit that I can adapt to ground the 1500 in an electrical out let using the ground plug.

 

[Ron Gorski]

My Chargemaster is probably close to 15 yrs old. I am running the modified settings published here many years ago that were provided by the RCBS rep.

I usually have very good SD/ES with my Chargemaster thrown loads.

Had some time today to perform a test.

30.0 gr Varget setting. 100 throws. Not a single overthrow.

Chargemaster and FX120i both warmed up for around 12 hrs.

I was a little surprised at the accuracy but it explains the good results that I have experienced.

Low 29.93
High 30.07
AVG 30.01
SD 0.0434
ES 0.14



There was only one 29.93 and only one 30.07. If I throw those out:

SD 0.04
ES 0.12

That is not accuracy. That is repeatability.

 

[kelbro]

That is not accuracy. That is repeatability.

Actually, it was both. The majority of throws (72%) were at 30 grains +/- .05 grains. None of the throws were outside the published (+/- .1) spec. That's both accurate and repeatable.

 

[Ron Gorski]

Actually, it was both. The majority of throws (72%) were at 30 grains +/- .05 grains. None of the throws were outside the published (+/- .1) spec. That's both accurate and repeatable.

One must check Uncertainty of measurement (accuracy) with a known good (calibrated) check weight. Just because the 30 grains were inside the +/-0.1 grain spec doesn't mean the scale was accurate.

 

[sgav8r]

Actually, it was both. The majority of throws (72%) were at 30 grains +/- .05 grains. None of the throws were outside the published (+/- .1) spec. That's both accurate and repeatable.

I personally wouldn’t consider +/- .05 to be “accurate” when dispensing Varget. That’s about a 5 kernel variance, from load to load.

Just because your CM can do that repeatably, does not make it “accurate”. An AutoTrickler will get you +/- .02, a 2 kernel variance, considerably more accurate.

 

[Straightshooter1]

I've been using a 1500 since about a year after they came out and was pleased with it until about a year and a half ago. I found that some throws were off a lot. Asked here and found the biggest issue is static electricity. RCBS says to wipe with dryer sheet or antistatic cloth every time you use it. What have you guys done about static elec.? I bought a little kit that I can adapt to ground the 1500 in an electrical out let using the ground plug.

I never let powder sit in my 1500 after my charging session. So, when I drain all the powder out I put a couple used dryer sheets in the canister (on occasion wiping the insides) and let stand until the next use. I've never had an issue about static electricity with it.

BTW: One other thing I do when using my 1500 is that I use a battery to run it.

 

[kelbro]

One must check Uncertainty of measurement (accuracy) with a known good (calibrated) check weight. Just because the 30 grains were inside the +/-0.1 grain spec doesn't mean the scale was accurate.

I have 30gr check weights.

I managed NIST certified cal labs for many years. I'm quite familiar with the differences between accuracy, precision, and repeatability.

 

[kelbro]

I personally wouldn’t consider +/- .05 to be “accurate” when dispensing Varget. That’s about a 5 kernel variance, from load to load.

Just because your CM can do that repeatably, does not make it “accurate”. An AutoTrickler will get you +/- .02, a 2 kernel variance, considerably more accurate.

For 1K loads, I use the CM to throw just short of my desired weight and trickle with the Dandy. I get 0 variance (within the scale's tolerance) and 0 overthrows. A little slower but still more 'accurate' than an Autotrickler.

 

[Straightshooter1]

For 1K loads, I use the CM to throw just short of my desired weight and trickle with the Dandy. I get 0 variance (within the scale's tolerance) and 0 overthrows. A little slower but still more 'accurate' than an Autotrickler.

I feel that's the best way to go about getting a consistent result. Likewise, I would throw short and trickle up. Though my trickling method was a little different. Since I used a clear straw and regulated the flow of powder through the straw, I'd have the CM throw short and as I could see the few powder kernels sitting on the edge of the straw, I'd just lightly tap the CM cylinder to trickle up as needed. Without being able to regulate that flow, there'd be way to many kernels bunched up sitting on the edge waiting to drop in order to control the trickle.

 

[wkdickinson]

I used a CM 1500 for probably 8 or 9 years. I was always suspect of the rounding algorithm they used. I did the the "settings" thing and built my own "nozzle" instead of the straw and all those things helped. When I bought a AutoTrickler V4, I did several studies (50 throws min) comparing the accuracy of the CM1500 scale, comparing the throws to the weight on the A&D FX120i (I only used throws from the CM1500 that were exact). What I found was that most were within the 0.10gn range, per the CM 1500 spec. But there were also far too many in the 0.20gn range.

 

[L.Sherm]

But there were also far too many in the 0.20gn range.

That .20 will absolutely throw a flyer in cartridges that use 35.0 and under.
It could also put you over max in smaller cartridges.