ChargeMaster 1500 Scale and W231 Powder

[stodd]

Hello Everyone,

I have a issue to run by anyone that can help. So I've been loading some 45 ACP with W231 powder for about 8 months now (this is when I started using W231, since it was so hard to find for sometime now). I'm using a RCBS Uniflow powder measure with small cylinder. I've got a RCBS ChargeMaster 1500 Scale. Both pieces of equipment are about 15 to 17 months old now.

Here is the question..... I've been loading 5.2 Grains of W231 using my RCBS Uniflow powder measure. I've loaded about 650 rounds with this setting on the Uniflow powder measure. I haven't touched the setting on it, as I'm working on getting a stock of 45 ACP loaded up before moving back over to my 9MM setting. So this morning I figured I could load a few more up and I came across an issue that I can't figure out.

When I went into the reloading room (inside the house, in a bedroom), I did as always fill up the hopper on the measurer and drop a few loads and set them on the ChargeMaster 1500 scale as always. When I did it this morning the scale said 5.0 grains not 5.2 grains. I calibrated the scale two times just to make sure things were right there.

I haven't touched the setting on the measurer so it should be dropping 5.2 grains, but the scale is now saying 5.0 grains. When I was loading the other 650 rounds in 3 different load sessions, the scale showed 5.2 grains each time.

The only thing I can think of is the temp in the house if a little different from the other 3 load sessions. It's getting a little colder outside, so inside the house is a little colder not much though. The heat is on most of the time to keep the temp in the house at about 74 to 78 degrees.

Anyone have any ideas why it looks to be dropping 5.0 grains vise 5.2 grains now without touching the setting on the measurer? Is it the temp?

Thanks..

 

[MEHavey]

The Uniflow measures by volume. As normal air moisture/temp goes
up and down, so will the weight of a given volume of powder.

Even though I use my Harrells' measure for almost everything now,
I always re-establish the day's "weight" setting on the measure
before starting a loading session.

No big deal.

 

[James2]

I see that happening too. Don't have an explanation except temperature and humidity. The temperature of the parts of the measure itself could make a difference. I would not worry about it.

I am with MEHavey though and always readjust for weight.

 

[Fatelvis]

I have experienced powder getting lighter over time also, especially if you use a little at a time out of a 8lb jug. I think it dries out.

 

[Fatelvis]

The question is:
Do you trust the volume, which you know is the same, or do you up the volume to make the weight? Hmmmm.....

 

[NeuseRvrRat]

in my experience, this is pretty common.

 

[arizona98tj]

Check weights.....you verified your electronic scale was properly reading 5.2 grs....or did you just calibrate it?

I have a 1500 too....with the powder measure attachment. I always do a sanity check with my check weights before and after a reloading session. I can't think of a reason why I wouldn't want to.

 

[stodd]

Yes (I always do the calibrate too) I checked the weight before and after the last load session, which was about 1 month ago. All of the checks before, during and after the load session was all at 5.2 grains.

I haven't loaded with W231 in colder weather yet, first time here. All of the other times I've loaded in the winter months was with bullseye and unique powder, which I never seen that happen before.

I'm not sure if I should adjust it so it's back at 5.2 grains again or not. If I raise the grains again that will increase the pressure right? Is this just something that happens with powder in colder weather? the grains go up and down pending on temp?

 

[arizona98tj]

I always trust my scale, since I can and do always double check it with my check weights.

 

[edfardos]

Make sure the grub screw which holds the dial to the actual plunger is tight.

But realistically, a .2 variance between sessions isn't uncommon.

Edfardos

 

[stodd]

Arizona98tj,
I also check my scale with the check weights all the time and things are always right on. So if I were to increase the grains back up to 5.2 grains, would that make it a hotter load and/or more pressure then? I would be putting more powder in then a month ago and that would cause more FPS?

Edfardos,
I haven't touched anything on the Uniflow powder measurer since the last time I loaded. So it should not of changed.

 

[noylj]

Note: in this case, volume trumps weight. Powder will lose residual solvents and it will gain moisture, thus the weight can go up or down. Neither has any effect on performance. Weight varies, but bulk density and volume of powder (and chemical energy of that volume of powder) stays the same.
It seems in the past 10-15 years, people have gotten overly anal about weight and forgotten 100 years of history of powder metering by volume. I don't know about today, but bench rest was ruled at least through the '90s with volume.

 

[BYJO4]

It is not unusual to see a small change in weight your powder measure drops from one loading to the next. This is why we zero our scale and drop a few test charges. Temperature or humidity can cause the change in your reading and a very slight adjustment to the powder measure will correct.

 

[Fatelvis]

Note: in this case, volume trumps weight.

That is what I thought, so I never turned the measure up to compensate for the weight. I would rather err on the safe side, especially when getting near a max load. When powder dries out and you're throwing bigger volumes (like for rifles i.e. 45grns. and up), the change can be much more dramatic, (over 1 grn.).

 

[dickttx]

Recently had the opposite happen.
Reloading in my garage, when the weather changed my Lee Pro Auto Disk that always drops 5.3gn of HP38 was now dropping 5.5gn.
Since it is still under max I kept on using the same disk hole, but noted the different weight on my label.
I too wonder what it will be when the weather warms back up. Will that affect the loaded cartridge?

 

[LiveLife]

If the digital scale is located in the garage/workshop where temperatures go beyond average room temperature range, electronics may not operate consistently.

FA digital scales sold by MidwayUSA specified 59F to 95F temperature range and I use them inside with good consistency within .1 gr and the new FA DS-750 digital scale with flip cover also is consistent within .1 gr of two Ohaus 10-10 beam scales I have.

I do not know what temperature range RCBS ChargeMaster 1500 scale specifies, but if ambient temperature was the only thing that changed between the two weights, then I would try to duplicate the ambient temperature condition and try again.

Try this. Take the powder measure/scale inside the house without changing anything and let it warm up to room temperature so it is within the temperature range specified for FA scale of 59F-95F. Once the machine warms up, take several sample measurements. If the readings change or returns to 5.2 gr, it may support my theory.

 

[LiveLife]

I just reread the OP and saw that reloading room is inside the house.

The only thing I can think of is the temp in the house [is] a little different from the other 3 load sessions. It's getting a little colder outside, so inside the house is a little colder not much though. The heat is on most of the time to keep the temp in the house at about 74 to 78 degrees.

So, if the ambient temperature is kept the same, you still have an additional factor of heating that may be drying out the moisture out of the air. As others posted, if your powder measure meters by volume, this may make the charges lighter due to less moisture in the powder. I am not sure if this is the case but may contribute to the lighter .2 grain measurement.

I reload indoors with ambient temperature range of 68F - 78F with A/C in the summer and gas fired heating in the winter. Since I use Lee Pro Auto Disk, powder charges are dropped by volume. Using the same Auto Disk hole, I don't recall seeing a .2 gr change with W231/HP-38 on the Ohaus 10-10 scales or the FA digital scales.

 

[Walkalong]

Note: in this case, volume trumps weight. Powder will lose residual solvents and it will gain moisture, thus the weight can go up or down. Neither has any effect on performance. Weight varies, but bulk density and volume of powder (and chemical energy of that volume of powder) stays the same.
It seems in the past 10-15 years, people have gotten overly anal about weight and forgotten 100 years of history of powder metering by volume. I don't know about today, but bench rest was ruled at least through the '90s with volume.

Exactly.

If you have a chrono use the same measure setting and see if you get the same results. Digital scales can be finicky. I bounced mine off the tile floor in the kitchen and deposited it in the trash can. I have had a couple of times with thrown charges where I had to scratch my head and wonder if I logged a setting wrong or something. Hate that when it happens, but it is rare.

 

[LiveLife]

Digital scales can be finicky.

+1.

When I got my second new old stock (NOS) Ohaus 10-10 scale, I did sensitivity testing using thinnest copy paper cut to 1/4" x 1/4". The two Ohaus scales detected and measured single piece of paper each time but the digital scales did not detect until 2-3 pieces were placed and barely read 0.1 grain.

I wonder if OP could do this sensitivity test to see how the Chargemaster does? Of course, depending on the weight/thickness of the paper, readings would vary.

 

[stodd]

So by increasing the grains from 5.0 back to 5.2 will not change the performance and/or pressure?

I don't think I'm all that worried about it, since I'm somewhat at the low end. One of my books says 5.0 min to 5.7 max and the other book lists it 5.2 min to 5.8 max. So I'm not worried about that. I just wanted to understand what was causing the change and if I move the charge up will that impact the outcome and pressure.

Thanks guys.

 

[Walkalong]

My guess is you did something wrong, or the scale was being affected by something one of the times. Hard to figure out from here though. It is very frustrating when something like that happens, leaving us wondering what we did or what happened.

 

[MEHavey]

"...did sensitivity testing using thinnest copy paper cut to 1/4" x 1/4".
The two Ohaus scales detected and measured single piece of paper
each time but the digital scales did not detect...."

Actually, the digital did detect, but is programmed to zero itself when within a tenth or two of Zero weight.

This is part of the "tare" process where the net powder weight is shown as the difference between Zero-Tare and full pan.

While I occasionally run my checkweights (when feeling paranoid), my more usual running check is that of:
- Does the scale read (-)'68.1gr' when the pan is lifted off of it
- Does the scale return to zero when the empty pan is placed on it

 

[LiveLife]

I would still be curious to rule out the effects of temperature.

Anyone with a ChargeMaster interested in doing a room temperature (74F) vs cold garage (45F) sampling of 5.0 grains W231/HP-38?

The powder in the hopper probably needs to stay overnight to allow for contraction.

 

[stodd]

Thanks everyone for your input. I'm going to load up a few at the current setting, which is showing 5.0 grains atm and then up it back to 5.2 grains and see what the difference is.