RCBS needs 3 mods to be accurate:
1) insert a drinking straw,big one) into the trickle tube - stops the granules clumping up and over charging.
2) Tilt it back a bit by putting something under the front feet about 15mm - 20mm high.
3) Reprogramme the electronic setting as follows,exerpt from another forum):
For anyone using the RCBS Chargemaster, I have modified mine recently and I am very pleased with the results. Some time ago I posted a thread about sleeving the trickler tube to improve the accuracy and eliminate overcharges. This worked, but it slowed the unit down and I found myself waiting for the charge to finish after seating the bullet on the previous charge.
I decided to revisit the programmable parameters on the unit and see if I couldn't get some of the speed back. Well it worked, ... really well. If you press the Edit and Enter keys at the same time you enter the programming mode for the unit. The first three parameters that come up are:
HSP_A1 15.68
HSP_B1 3.42
HSP_C1 1.08
There are many more parameters after these that can be accessed by repeatedly pressing the Enter key. I attempted changes to some of these other parameters, but they did not behave as I expected them to, so I ended up leaving them alone. After the last parameter is passed, the unit resets and starts again with the changed values. As I understand it, these three values determine the shift points below the desired charge, in grains, for slowing down the trickler. To change these values you wait until the existing number is visible and then enter the new number and press Enter.
I noticed that the trickler was spending too much time at the slower speeds, so I decided to move the shift points closer to the desired charge. I also changed the sleeve in the trickler tube to a thin-walled smooth metal tube, instead of using the tube from my manual trickler as I had been doing. The purpose of the sleeve is to cover the threads in the trickler tube. The trickler tube is inclined slightly,as opposed to hand tricklers which are typically level) and the unit seems to have problems with powder clumping due the threads. A soda straw of the right size would work also, I think, but I thought metal would have less problems with static electricity. I change the parameters to these settings:
HSP_A1 6.00
HSP_B1 2.00
HSP_C1 0.50
These values are optimized for 24.5g of RL-15. Other weights or types of powders might not work as well. With these settings, my Chargemaster throws 24.5g of RL-15 in 10 seconds, without overcharges. It runs at high speed for about 5 seconds which gets the charge up to about 22g. It then slows down for a couple of seconds and then finally finishes with a couple of "bumps" which usually only drop a couple of grains of powder. If you wait for the unit to stabilize, show the count, and then return to the weight display, it takes about 15 seconds most of the time. Occasionally it takes 20 seconds if the powder doesn't cooperate during the final slow trickle.
Before these changes, it was taking about 45 seconds to get a charge, and I was spending too much time waiting. Without the changes to the programming, the only trade-off I could make was sleeve diameter. Bigger was faster, but also less accurate. This way I get the accuracy AND the speed. You can fiddle with the parameters as much as you want if you are not satisfied with the performance. You can always set them back to the defaults.
Good luck, and happy programming.
p.s. - I meant to mention the fact that the default values from RCBS are, by necessity, a compromise that has to satisfy everyone from the 40 S&W reloader up to the 375 H&H reloader with all brands powder. I only reload one caliber using one powder with the Chargemaster, so it only makes sense for me to optimize the unit for my situation. Too bad RCBS doesn't see it this way, and make the reprogramming information more available.
Thanks for the parameters! I'd tried getting RCBS tech support to send me the information, but they basically refused to tell me anything unless I was sitting in front of the machine at the time - apparently they don't want this sort of info getting out. I had bought my Chargemaster after reading the test reports on 6mmBR.com and seeing reports of 8-12 seconds for 42gr of 4064 - I though "Heck ya!". Reality was in the 30-45 second range, which meant a lot of thumb twiddling waiting on the dispenser, usually because of the early slowdown. For .223, it was just ridiculous.
At any rate, I tweaked the first three parameters above on mine... think I'm at 7.5, 2.5, and 1, but I might need to adjust that some more,running for 40-50gr charges for .308, 6.5-284, etc.) as the high speed doesn't quite cut out in time - but it's a heck of an improvement and its nice to have the ability to control this stuff for myself finally.
BTW, a 1" section of McDonalds drinking and a thin strip of duct tape to hold it in place works just fine - no static issues whatsoever, and I've loaded hundreds and hundreds of rounds like that. Looks a little redneck, but it works.
Over charges still occur but *very* rarely, as the powder doesn't 'clump' near as much with no threads in the tube,straw) for that last inch. Even if it does... my thumb n forefinger are pretty well calibrated to where I can lift the pan, pinch off 0.1-0.2gr and throw it back in the hopper, put the pan back on the scale... just right.
