For my precision rifle loadings I weigh all of my charges but use a RCBS Charge Master 1500. This will weigh charges to a resolution of 0.1 gr., but I worry that the actual variation is greater than this. My velocity SD & ES is not where I would like them to be & I attribute a lot of this to deviation in charge weight. What is the next step up in precise powder dropping without spending a crazy amount of money?
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Accuracy of RCBS Charge Master 1500
- Thread starter MMH
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I use a 1500 as well and have for 10 years.
I typically see .1 to .2 swings. To help control this I have made the few program adjustments with speed and slowdown. Added the insert and bought a good set of check weights.
I also have it on a dedicated circuit with a good GFCI power strip with serge protection.
I also added a little dandy tricker. Set the charge weight .2 below then trickle up to the charge weight one curnal at a time.
This noticeably helped in the swings and lowering SD’s and ES.
Inserts were $15 I think and the tricker was $125 used form a member here on the hide but I think they are $150-$175 new.
I typically see .1 to .2 swings. To help control this I have made the few program adjustments with speed and slowdown. Added the insert and bought a good set of check weights.
I also have it on a dedicated circuit with a good GFCI power strip with serge protection.
I also added a little dandy tricker. Set the charge weight .2 below then trickle up to the charge weight one curnal at a time.
This noticeably helped in the swings and lowering SD’s and ES.
Inserts were $15 I think and the tricker was $125 used form a member here on the hide but I think they are $150-$175 new.
If you are careful, your CM will typically give you a statistical performance on the order of 0.3 grains ES for large batch samples.
This is just the nature of the CM electronics and resolution of the scale, plus the nature of powder kernels and how they fall from a tube.
If you are not disciplined, it is easy to have one give an ES of more like 0.4 grains for a large batch sample.
As far as not wanting to spend a lot of money and do much better..... wish I had some better news for you.
You will either be going really slow and tedious, or you will need to spend more money for the speed.
This is just the nature of the CM electronics and resolution of the scale, plus the nature of powder kernels and how they fall from a tube.
If you are not disciplined, it is easy to have one give an ES of more like 0.4 grains for a large batch sample.
As far as not wanting to spend a lot of money and do much better..... wish I had some better news for you.
You will either be going really slow and tedious, or you will need to spend more money for the speed.
+1, this is always worth a look too.
But when it is all said and done, you can run side-by-side on a good recipe put together with an ES of 0.3 grains against the same one with an ES of less than 0.1 grains and you will find out this spending on single kernel scales isn't just a Gucci thing. YMMV
Spherical powders suck in the Chargemaster, at least in my experience. I can get good ES and SD using my Chargemaster with powders like vv N140, Benchmark, IMR 3031 and 7828 when i use powders like Ramshot Magnum, Winchester 760 or anything spherical they go to crap.
Also when trying to get a low extreme spread try changing primers,that can be all that’s needed.
Good brass and prep work, consistent neck tension are more important than a couple sticks of powder.
Also when trying to get a low extreme spread try changing primers,that can be all that’s needed.
Good brass and prep work, consistent neck tension are more important than a couple sticks of powder.
Yep, I was estimating that my deviation was in the 0.2 to 0.3 ballpark. I usually drop 0.2 gr. low and then use a manual trickler until the scale just bumps up to the target weight. For example, my 178 gr. 308 load is 43.0 gr. of varget. I set the chargemaster to 42.8 and then trickle. As soon as the scale reads to 43.0 I immediately stop. When I get in a hurry I overshoot & then dump the powder and drop again.
Also wonder how much drift there is in the scale. I am thinking that I should check periodically to make sure that recalibration is not necessary.
Find a decent check weight and occasionally sample it. This habit will teach you a lot about the scales null and gain drift.
Remember to check zero, and the gain, not just one or the other.
Temp changes where you are working are a driver for problems. It is good to also keep a temp humidity gage where you are working.
I have worked with the 1500 for at least 10 years and performed many test with various powders and this is what I have learned.
The scale resolution is not a problem.
The variation in charge weight is mostly a function of single tube dispenser. It is also related to the speed of the reloading.
There are instructions on the internet to help program the unit to speed it up, slow it down, reduce overthrows, etc. These can be used and the actual inputs are powder specific.
The infamous straw modification used in conjunction with programming can reduce the variation in the number of kernels dropped in the trickle mode. I use the top of a 243 case on the outlet to reduce the trickle drops.
Speed is the enemy of precision.
With programming here are the results of 27 charges of 8208XBR 225.4 gr checked with a little GEM 20 scale.
The scale resolution is not a problem.
The variation in charge weight is mostly a function of single tube dispenser. It is also related to the speed of the reloading.
There are instructions on the internet to help program the unit to speed it up, slow it down, reduce overthrows, etc. These can be used and the actual inputs are powder specific.
The infamous straw modification used in conjunction with programming can reduce the variation in the number of kernels dropped in the trickle mode. I use the top of a 243 case on the outlet to reduce the trickle drops.
Speed is the enemy of precision.
With programming here are the results of 27 charges of 8208XBR 225.4 gr checked with a little GEM 20 scale.
In general, in 223 most powders will work out to between 11 and 12 fps/0.1gr. In 308/6.5CM its around 5 to 6fps/0.1 gr.
Looks like Doom got the same results for SD's and ES's doing the same kind of weighing, only . . . I also looked at some of my other scales to see how they staked up.
My CM 1500 was frustrating me with the its trickling and letting clumps fall in. I adjusted the programing to slow down the trickling function AND added a straw method that is adjustable, which helped a lot in getting it to trickle decently.
Velocity change will depend on things like the load, temperature, its velocity and the size of the bullet you're using. But, just to give you some idea, on my .308 with 168 SMK's being pushed by 42.0 gr Varget, the difference is ~12 fps. Obviously, is makes a bigger difference with a smaller cartridge.
Will the 50 & 100 weight that comes be good enough or do I need a more refined weight set? My temp should be fairly stable. The only local heating may be from the heating that comes from the weight scale itself. on a given 'lot' I do not think there would be significant variation. Between 'lots' probably. Worth documenting?
Its best to get an assortment of check weights. Seval different options from various suppliers. I have the RCBS kit that .5gr-20gr.
its $50.
its $50.
Like texastonk says above, a small variety set would be better than the ones provided.
Units like the CM come with a set of weights intended to help set "the gain" of the scale to calibrate it.
Usually, when we calibrate a load cell, we will use something like the half capacity and full capacity of the cell. That serves to set the gain at or near the full scale for leverage to get the best results. The middle value is used to insure linearity, so in effect you get a three point line when you include the zero, the 50, and the 100.
When we are loading, we are typically at a low fraction of the cell's total load capacity. For example, 100 grams is 1543 grains and you are typically loading way lower, so while you work it is best to watch at the levels you load at.
I would tend to either get a cheap set of check weights or make them up yourself, and try to set one at the exact value of your favorite loads. Record the value of your check weights when you have your calibration spot on, and then repeat those observations a few more times to be sure. Then while working...
Occasionally, verify the zero (null) and then place that check weight on the scale and observe.
Did the zero drift?
Did the gain drift?
Is the temp in the work area the same as when you calibrated or started working?
The troubleshoot list can get lengthy, and hopefully you don't need to worry about it. Make or buy yourself some check weights, they will keep you out of trouble. Good Luck.
Thanks for posting this, again. I also did the 4064 but I can't find the data but it was similar to yours.
Was the 12 fps for 0.2 gr?
last 40 rounds of 41.2 H4350 were an ES of 26 with a SD of 7.2 avg velocity 2778 out a 24" barrel in 6.5CM. I'm not sure if thats good or not. if the scale starts drifting from the 160g with the metal cup down to 159 I recalibrate. I usually get 3-4 overcharges per 50.
I have a Match Master and with mil vet discount it came in at a reasonable price. I run it in match mode but I don’t compete and I’m retired so I’m not trying to load 250 rounds after work so speed isn’t a priority for me.
I have thankfully avoided the ATv4 and ST quagmire.
I’m on the list for the Ingenuity dropper…if it ever come to market. Until then, I’ll stick w the MM.
I have thankfully avoided the ATv4 and ST quagmire.
I’m on the list for the Ingenuity dropper…if it ever come to market. Until then, I’ll stick w the MM.
The discussion is actually concerning precision not accuracy.
This +/-0.1gr total accuracy including display resolution which is the limiting factor along with dispensing accuracy and calibration weight accuracy class. The actual internal scale accuracy and precision is better than that.
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I know this is not what most people hope for when they buy the Chargemaster but I use mine to throw a a couple tenths light and then hand trickle the rest. Once you get in a good rhythm its doing the heavy work while you hand trickle the last grain or two. The reality is that in most calibers that I shoot a tenth either way isn't going to kill me. I am constantly reminding myself that I am not a benchrest shooter, just an old fat guy trying to shoot "Minute of Man" for fun.
Edited to ad: I use an ancient Ohaus 1010 scale for final weighing.
Edited to ad: I use an ancient Ohaus 1010 scale for final weighing.
What ATv4 and ST quagmire? Was just looking into that to actually see if i can get better groups on paper at 500 600 yards versus using my Chargemaster.
Read the ST thread. Last few pages will do it. As for ATv4, seems like people like the V3 far better. Might want to look at the thread too.
Cheers
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