Tip for RCBS Chargemaster Users

[Ledd Slinger]

The RCBS chargemaster has always walked a very fine line between love and hate amongst hand loaders. I personally love them and have had zero issues after tuning and modifying them correctly.

People who use the CM most likely know about the programming mods and drinking straw drop tube mod. There are also custom aftermarket brass drop tube inserts that I've heard work very well to give the same effect as the drinking straw with avoiding overthrowing of powder charge weights.

I have 2 CM's and the most recent one I purchased still needed the drop tube mod. Well I couldn't find a drinking straw that would fit. McDonalds straws used to fit perfectly, but it would seem they have changed to a smaller straw these days and they dont fit correctly. So while not wanting to purchase and wait for an aftermarket brass insert to arrive, I needed to devise another way of modifying the drop tube to get the same great performance I have always had on my other CM.

Looking around the reloading room, I found the solution. A piece of 10mm Auto pistol brass. The 10mm brass ID (case mouth side) is almost a perfect fit on the OD of the drop tube. Cut the base off, chamfered and deburred, then adhered it to the drop tube with a very fine film of RTV silicon. The base end of the brass is about 3/8" from the end of the factory threaded drop tube. Works like a charm




Here is the old style McDonalds straw inserted on the inside of my first CM drop tube. Works great.




Here is the finished 10mm Auto brass fashioned to the outside of my other CM drop tube. Also works great.

 

[Targetbanger]

I love mine, but the only thing I don't like is I can only load in .10's and not .05's. ( I think I typed that right). If I can I haven't figured out how to do it yet. I've only had it for 3 weeks.

How I'm loading my loads is .10 under and then using tweezers dropping 1 grain in at a time to get my perfect weight. I've very happy with the results! I use the straw method too.

 

[rwj]

If they don’t already exist, there’s a business opportunity to make plastic plugs that thread into the drop tube. They can be offered having different diameter thru holes to vary the rate at which powder is dispensed.

 

[MN50Shooter]

I don't know whether he is still making them or not, we have a member that was making reducers for the tubes to help stop over throws. I bought one, and it works good, except on large extruded powder, such as Reloader-50. The McDonald's straw seems to work best with large extruded powders

http://forum.accurateshooter.com/th...serts-for-chargemaster.3846088/#post-36410118

 

[boltfluter]

I don't know whether he is still making them or not, we have a member that was making reducers for the tubes to help stop over throws. I bought one, and it works good, except on large extruded powder, such as Reloader-50. The McDonald's straw seems to work best with large extruded powders

http://forum.accurateshooter.com/th...serts-for-chargemaster.3846088/#post-36410118

Images for this seem to be blurred out. Does anybody have a clear image? May make a few of these if I can get a good pic to work from. Thanks for any help.

Paul

 

[mikecr]

There is another action in this direction (tuning to single kernel dropping):
I installed a 10-ohm potentiometer inline with the motor drive, for fine calibration of drop rate with different powders. A source: https://www.amazon.com/dp/B00AVSECQ4/?tag=accuratescom-20

 

[boltfluter]

There is another action in this direction (tuning to single kernel dropping):
I installed a 10-ohm potentiometer inline with the motor drive, for fine calibration of drop rate with different powders. A source: https://www.amazon.com/dp/B00AVSECQ4/?tag=accuratescom-20
View attachment 1126793
View attachment 1126794

Mike,

That's a very neat feature that you added. Very nice.

Paul

 

[Ol’ Ed]

Not my original idea (can’t remember where I saw it, maybe on this website) but I took a McD straw and inserted it all the way in until it touched the back of the dispenser tube. I then pulled it out about a 1/4” and cut the straw flush. Different powders require the straw to be moved in or out. As I reload with different powders and find their “sweet spot” on the straw, I use a sharpie and, while the machine is dispensing, make a circle on the straw. I found that using this method, and putting the Chargemaster back to the original settings, I have 1 out of 10 overthrows of .1 grains, which usually is remedied by pulling out just one grain. It’s a little slower throwing charges but a lot more accurate. I’m happier with it.

 

[TAJ45]

One granule is = to .1 grains??
Maybe that was what pushed it over the threshold for the next tenth? Therefore not a full tenth "off"?

 

[Ledd Slinger]

Not my original idea (can’t remember where I saw it, maybe on this website) but I took a McD straw and inserted it all the way in until it touched the back of the dispenser tube. I then pulled it out about a 1/4” and cut the straw flush. Different powders require the straw to be moved in or out. As I reload with different powders and find their “sweet spot” on the straw, I use a sharpie and, while the machine is dispensing, make a circle on the straw. I found that using this method, and putting the Chargemaster back to the original settings, I have 1 out of 10 overthrows of .1 grains, which usually is remedied by pulling out just one grain. It’s a little slower throwing charges but a lot more accurate. I’m happier with it.

I inserted the straw and did the programming mods on my original CM before I ever threw the first charge with it. It has never overthrown a single charge with thousands thrown. I have thrown powder from long extruded to small spherical ball powders and everything in between. Never touched the straw once. Works perfectly on all powder where its at. Been a handful of years since I bought the first CM, but if I remember correctly, the straw insert is about 1" long so maybe half way up the drop tube?

So as said above I never tried my first CM without the straw or programming mods. The other CM, I did try without any mods and it would overthrow charges bad. Probably 8 out of 10 charges were overthrown. With modifications complete, it's not overthrowing anymore.

 

[Ledd Slinger]

Another thing...
I do NOT mount the CMs level.
The rear of each CM is raised up by adjusting the back feet a good bit higher than the front. To me it seems like extra slope on the drop tube helps powder to flow better without building up at the end so when its trickling it can really fine tune the final weight. I can watch it bumping and dropping only 1 to 2 kernels as it throws to the final 0.1gr target weight.

I have check many of the throws on my original CM with my AND FX-120i scale and they are all within .04gr of the .1gr target weight they threw. Which with some of the extruded powders is only 1 kernel. I think the worst I saw was .06gr off target weight. Of course I dont check every charge, but i have checked about 30 or 40 of them here and there over the years and they were always so close that I stopped cross checking them on the FX-120i.

Have not cross checked the new CM with the FX-120i as I just finished the mods and havent thrown very many charges.

 

[mikecr]

One granule is = to .1 grains??

No. A kernel of H1000 is ~0.04gr, Varget is ~0.020, H4350gr is ~0.025gr.
But you can learn to operate a 0.1gr scale in such a way as to detect differences by the kernel, even while it can't measure it.
Similar to earlier posted by Ledd, you can use a more accurate scale to calibrate and also to get a feel for what it takes to show you correct drops. Much of it is timing.

I watch the rate of kernel drops to scale changes.
I don't believe what my RCBS 'locked in' reading is, as that's just their programming to indicate desired..
So after a charge I lightly disturb the pan forcing remeasure at the scale's sampling rate(bypassing charge programming). If the scale quickly locks right onto my goal weight, or roams around it a bit, this validates for me what my gut feeling said with that charge.
My gut feelings were calibrated comparing scale response and readings with an Acculab scale.

 

[_Raining]

If I can I haven't figured out how to do it yet.

The chargemaster only has a resolution of .1 grains, can't do .05

 

[jepp2]

The chargemaster only has a resolution of .1 grains, can't do .05

Watch this video. Eric got 0.04 on a short test.

 

[_Raining]

Watch this video. Eric got 0.04 on a short test.

That video is how to reduce ES by trickling up. Unless I am miss-understanding the person I quoted, he wants to be able to enter in 34.35. He might be able to put a half grain weight on the pan and zero it then take the pan off but the charge masters accuracy and ES is going to depend a lot on the type of powder and unless you have another expensive scale to verify, you will never actually know what that ES or avg value is. Chargemasters are fine but if you have the cash, an FX 120i + autothrow/trickler gives you speed and peace of mind.

 

[jepp2]

Unless I am miss-understanding the person I quoted, he wants to be able to enter in 34.35

I didn't take his comment that way at all. Granted the DISPLAY on the Chargemaster only displays to one decimal point. But that isn't the accuracy of the SYSTEM. And from the description shared, throwing a tenth light, and dropping individual kernels on the pan until the display changed would approach system accuracy.

Chargemasters are fine but if you have the cash, an FX 120i + autothrow/trickler gives you speed and peace of mind.

No argument there.

 

[Rick300]

I found on mine that where it "breaks" to the next tenth is very consistent. So, like Eric Cortina shows, if you set the charge a few tenths low and trickle up, you will soon get a feel for how close the charge is to the set weight. When I got my FX 120i, I checked it doing that and was able to keep it to +/- .04 - .05 pretty consistently. I did reprogram it and bought the insert which helps.

 

[RustyNutz48]

Agreed on the reprogram I’ve found the straw method to be very helpful as well. Cut the notches in the straw and make sure it extended all the way back so the inlet for powder can be adjusted. I’ve heard of some guys putting a mark on the straw to reference which powder throws well for that adjustment.

 

[Ol’ Ed]

/\ /\ /\ That’s what I was saying in my earlier post (inserting the straw all the way back, then pulling it out about 1/4” and then adjusting/marking it for different powders). I tried the notches and it just didn’t seem to work that well, so I went back to smooth. And the parameter changes didn’t seem to work that well, either, so I set them back to the factory settings. I guess what I’m learning from this is that Chargemasters are a lot like rifles: each are maybe unique enough that you just have to experiment to find where they’ll “shoot”.

 

[Nick Caprinolo]

My big problem with the Chargemaster is dealing with the tare weight. It is continually changing and must be zeroed from time to time.

When I called RCBS, they told me it did not matter and did not affect the accuracy of the scale. True the scale still reads zero when the tare drops a few tenths grain, but if it goes down more than that, the scale does not measure correctly.