Scales

So I have recently been pondering my Chargemaster and its accuracy. Last night I had a little time to play with it so I turned on the CM and dug out my old RCBS beam scale. I picked up apiece of 45 colt brass off my bench and weighed it on the CM then on the beam. They were 0.5 grains different. I started to wonder wow is the CM really that bad?

Then I noticed the amount of dust coating the beam scale so I took it apart cleaned it up put it back together and re weighted the case and came to within 0.3 grain of the CM.

This was only a couple minutes after turning the CM so I gave it about 5 minutes and picked another piece of brass and weighed it, this time the scales were 0.2 grain different, so I waited another 5 minutes and the same piece of brass weighed 0.1 grain different on the two scales. At that point I ran out of time and it was time to meet some folks for dinner, but I can only assume that the longer I let it warm up the better it would get. I have always let it warm up for at least 30 minutes before I use it.

In the end I do believe the beam scale is more precise. I weighed a couple things where the 0.1 grain adjustment on the scale moved 1 notch would be to high/low, so it can discern less than a 0.1 grain difference, just cant tell you exactly what that measurement is.

After doing only a couple of weighs on the beam scale I already find myself flashing back to watching a swaying pan and a bouncing needle. lol I need a big plastic cover to cover the scale/pan like the CM has.

The good old days! I have a number of powder delivery devices, but have used a Lee Safety Scale to verify charges for a heck of a long time; 30 years? While watching it dampen one day, I thought about what would slow it down. I had an allen wrench sitting on the bench, so I placed it so that the short end of the wrench was under the pan. It is amazing the effect metal has against its own kind. It cut the oscillations by a third or fourth, near nothing.

Here is something else that I did just as long ago. Using a Lyman check weight set, I verified the calibration of the Safety Scale from zero through 60-grains. Then, I used half and one-grain check weights to mark the index face. This small effort, along with the allen wrench, saves a heck of a lot of "scale" time.

The RCBS CM scales will vary in 2 ways. 1- when they sit idle for a period of time, the read out of the weight will change. I've left a powder charge in the pan and come back a few hours later, and it read something different by several tenths of a grain or more different. 2- the variation of the scale is within +/- .1 grains. This means higher or lower by .1. I find this to be about right. One of my set ups I let the CM throw a charge and then transfer it to my high end scale that is accurate to .02 grains. The powder charge can easily be off by .1 either way.

If you keep it warmed up and keep zeroing out the scale, it will help it be more consistent. Also, keep your phone away from it, away from florescent lights, and let it warm up for 30 minutes, it will improve the consistency. For what the CM is, it's a great machine.

Ranch Dog, I will give the allen wrench a try, I had one sitting on the bench, just not under the scale lol.

Think I am at least going to complete my load development for my 7-08 with the CM throwing low and trickle up on my beam scale. After I settle on a load I may load a few on the beam and a few on the CM and compare.

If you get inconsistent variations between the 2 scales, it will drive you crazy on what the actual weight is. I would pick one scale and stick with it.

If you have a chronograph, your beam loaded ammo will have a lower ES.

I don't now, but plan to before I shoot the new rifle. I had never seen it before, but they make a much simpler/more cost effective version of the magnetospeed, think im going to pick one up before my shoot.

I'm going to study how to get a Magnetospeed in position without clamping it to the barrel. They now make a device to do that, but I'm not spending what they want for it.

Having a chronograph will be fun, ive never ran any of my loads over one. Will have to check some of my other long time loads ive been using.

And check then now, as well as our first cold snap. Using temp sensitive powders, it will show up. If you ise them.

As far as I know all my powders except IMR 4350 are temp stable and with the changing from 243 to 7-08 im loading the IMR anymore. I load H 4350, 4831, and benchmark.

Well I weighed out the ladder last night. 7mm08 175 grain ELDX seated to max mag length 2.955 oal starting at 10 @ 39.9 grains of H4350 to foul/sight and then every .3 grains to 43.2.

At what distance are you going to shoot the ladder test?

I’m curious to see how the 175s play out. I remember thinking when you started this project that was too heavy for 7-08 but with the longer barrel you chose and being able to seat them that long you might make the break.

If you run the loads in your other rifles across the chrony you may find that you’re no where near the speed you think you are. That’s most peoples experience anyway.

300 hopefully.