RCBS vs Mack - Scales

[Kelly Timoffee]

This afternoon I pulled some loads that I didn't use during a test.

I loaded them with the Chargemaster combo.

I recently received a Jennings Mack 20 to try help my reloading consistency and haven't used it yet.

I figured I would weight the powder charges to see what the variation was between the two scales.

What I found was a bit of a shock.There was over 3/10th's of a grain difference in some of the loads.

To some that may seem like very little and to some I am sure it is a lot.

Just some FYI for everyone out there, but which one is out???

 

[Moose308]

You should be able to come up with some check weights. Calibrated chrome-plated brass weights which are guarenteed to be 50g or whatever. That should tell you which is totally correct.

Now, to put things in a different perspective. It doesn't matter.

Unless you are reloading on different presses, using different scales, in different locations, it really doesn't matter which scale is 100% correct. If you are always using one scale, then you just load up using that one. You are really going for consistency more than anything. If you find a load is shooting great, or poorly, you just fiddle with a few grains here and there to your liking. So long as you are always using the same scale, and getting consistant throws, I wouldn't loose any sleep over it.

 

[warrenb]

Now, to put things in a different perspective. It doesn't matter.

Unless you are reloading on different presses, using different scales, in different locations, it really doesn't matter which scale is 100% correct. If you are always using one scale, then you just load up using that one. You are really going for consistency more than anything. If you find a load is shooting great, or poorly, you just fiddle with a few grains here and there to your liking. So long as you are always using the same scale, and getting consistant throws, I wouldn't loose any sleep over it.

Agreed. I know my mack 20 weighs around 1/10th grain over. I did'nt get the check weight so I can't re calibrate it. But I use it consistantly to get consistant charges. I check it periodically against my RCBS 10-10 beam.

I also have a marked penny that I use as a check weight everytime I start a loading session.

 

[Kelly Timoffee]

I guess what I am getting at is that one of the scales varied either the load it dispensed or the load it weighted by 3/10ths.

I have check weights on order to confirm the Mack calibration when I start using it for loading.

 

[LongBomber]

ah variance from round to round, not from scale to scale. 3/10th's does sound a little high. Do you have any electrical interference or air movement (heat register etc) around your loading area?

 

[KDX]

I've read somewhere that having the furnace or AC cut in while running the ChargeMaster could cause it to veer off course a little bit. I've never checked mine though.

 

[wapitiwhacker]

I have found that the Mack 20 tends to drift a fair bit. Watch the display every time you remove or replace an empty pan. Eventually it will be off the normal reading by a fair bit and needs to be rezeroed with the tare button. It also does not take to trickling well. If you change the charge weight by a very small amount it will tend to want to zero that change out. I take the pan off the scale every time I trickle any powder in. Then re-weigh the entire charge. It's a pain, but the scale stays zeroed longer.

 

[warrenb]

I have found that the Mack 20 tends to drift a fair bit. Watch the display every time you remove or replace an empty pan. Eventually it will be off the normal reading by a fair bit and needs to be rezeroed with the tare button. It also does not take to trickling well. If you change the charge weight by a very small amount it will tend to want to zero that change out. I take the pan off the scale every time I trickle any powder in. Then re-weigh the entire charge. It's a pain, but the scale stays zeroed longer.

Yep this is by no means a great scale. But it does work so long as you carefully watch it and get used to its foibles.

 

[Boomer]

There are two problems you need to consider, firstly does your scale provide repeatable accuracy, and the secondly, does it read the true weight? Any object can be weighed and reweighed a number of times to determine if your scale is repeatable, but you need a scale weight check set to determine if you are getting the weight your scale tells you you are. IMHO, repeatable accuracy is more important than the correct reading, but you do need to be aware that there is a difference from the true weight.

 

[BCboy]

I have the chargemaster and a rcbs 10-10 as well , I always use the check weight from the 10/10 after the chargemaster is caliberrated and it seems to be bang on . I do notice when I zero the pan it weighs 149.6 but after a while when I pull the pan off i will get 149.7/149.5 but it always go's to -0- when put back on ?

 

[tjhaile]

I have found that the Mack 20 tends to drift a fair bit. Watch the display every time you remove or replace an empty pan. Eventually it will be off the normal reading by a fair bit and needs to be rezeroed with the tare button. It also does not take to trickling well. If you change the charge weight by a very small amount it will tend to want to zero that change out. I take the pan off the scale every time I trickle any powder in. Then re-weigh the entire charge. It's a pain, but the scale stays zeroed longer.

I have a Mack 100 and I concur that you definitely have to make sure that the display reads the same when you remove the pan. The scale is calibrated with the weight every time I turn it on and I frequently check that it is properly zeroed while operating. A calibration weight is an absolute must-have item for an electronic scale.

Generally speaking, balance beam scales are better suited to trickling than electronic ones.

 

[notsorichguy]

The problem is that the Chargemaster is only rated to be accurate to .1 of a grain. the J Mack 20 is rated at .02 of a grain.

The differance you are seeing is with-in peramiters on the Chargemaster, but the Mack 20 can see the diferances.

I use both scales. I have one rifle that I really see the difereances on with both scales. With the CM I have an average of 38 fps (SD) on my 'plinking' load. With my 'accurate' load off the JM20 the SD is around 8 fps...... This is only revelant in one of my 30 rifles. It's the only that you can see a differance in.

There-in lies the rub. Just because you can weigh the differance doesn't mean your rifle can tell the diffeance......

The JM20 is a more accurate scale, because it is more precise, it shows variations easier and to a greater extent.

I only use the JM20 when I load for 2 rifles. All others get thrown (plinking) or weighed with my chargemaster combo (hunting).

Cheers!