Range Report RCBS Chargemaster and Standard Deviation

R

rg1911

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Oct 24, 2012
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#1
A search of the forum didn't come up with the answer (although I may have missed it).

Since a low SD is usually a good thing, I've been weighing each load of H4350 for my .260 Remington because even my Harrell's powder measure will show a .2-gr difference from one throw to the next (so a spread of close to 1/2 grain).

My individually-weighed charges are showing an SD of 8 fps over my Oehler chronograph. The thrown charges were showing an SD closer to 25 fps.

Loads are currently thrown, weighed on my RCBS 10-10 balance beam scale, and trickled up to the desired charge (42.0 grains). This takes quite a while.

(My 10-10 scale will react to as few as 2 granules of H4350. According to the scale, approximately 10 granules is equivalent to 0.1 grain.)

Based on the many positive reports here, I've been giving serious thought to buying an RCBS Chargemaster. However, I have not found a report that listed the SD of charges thrown by the Chargemaster.

Has anyone done this and, if so, what were the results? (Using the Chargemaster to throw a low charge and then trickling up, as some people report doing, does not seem to offer any improvement over my present method.)

Thanks you,
Richard
 
#2
I guess I am confused. You are saying that you want to know the SD of the Chargemaster via muzzle velocity? That seems like a strange question. Really what you are getting with the Chargemaster is accurate weights of powder. I think comparing the two measuring systems with your muzzle velocity is comparing apples to oranges. There are too many variables when trying to get SD to measure the powder charge.

Meanwhile, you do not throw a low charge on a Chargemaster and then "trickle up". It does not work that way. You simply punch in your desired weight of charge, hit "dispense" and it does the rest. If it is over or under, it will tell you so. You can see the reading to the nearest .1 of a grain digitally. Most of the time, if there is an error, it is over. But if it is under, it will trickle a bit more until it is complete.

I hope I answered your question. Maybe you could clarify the question if I did not understand you correctly.
 
#3
My apologies; I guess I wasn't clear. I would like to know the standard deviation in feet-per-second of loads that were thrown using the Chargemaster without setting it to throw under the desired weight and then trickling up to the desired weight. As I wrote, some users report that that is what they are doing.

In other words, what does the chronograph report about how consistently the Chargemaster throws charges? For instance, if those loads show an SD of 25 fps, I'll keep individually weighing my charges.

Richard
 
#5
Interesting question, and I have an answer from my own personal experience:

I consistently get an SD of around 10 with 38.9 gr H4350 out of my 6x47L and an SD of around 12 with 42.9 gr H4350 or 43.3 gr Accurate 4350 from my 260 Rem.

These numbers are from finalized loads; I've had bigger numbers during load development. I'm not sure I can shoot the difference at this point, so I'm not going to spend a whole lot of time chasing better numbers.

Thanks for starting the thread; I'm really looking forward to seeing what numbers others are getting.

I've only been reloading for a year, and everything I know about reloading came from TresMon's threads in the reloading section and from a wise man that was kind enough to take me under his wing and show me some wisdom.
 
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#6
My chargemaster (CM) is so much faster than throwing individual loads on a balance beam. I would say about 95% of thrown loads are accurate to desired weight and of the 5% that are not right on, 98% of those are no worse than a tenth high. putting a straw in the tube helps I heard but havnt tried it as when it goes over more than a tenth, its cause a clump falls in.

More interesting to me is that when I set the scale a tenth low, wait for beep and then hand trickle up to desired load, the "window" or sensitivity is much more lax in the set range, and MUCH more sensitive in the tenth above the setting. Meaning, if I set my load for my 6x47 at 35.7 grains and when it beeps at that load, it may take anywhere from 1-10 actual grains of poweder to kick it to 35.8 (my desired load) but after I reach 35.8, it will jump to 35.9 within 1-3 grains everytime. This added sensitivity has gotten my latest load SD down to 6, and I have never gotten anywhere near single digits before.

maybe im just overthinking it tho. Having a benchrest background, I just recently stopped measuring OAL of every loaded round. saved me a lot of time lol. And I don't think I am capable of shooting the difference of the work is actually saving me, but I think it will so that's all that matters :D

Regards,
DT
 
#7
My SD was unacceptable when I put my trust just in the CM (20-30 fps) for whatever reason. To remedy this issue and still maintain efficiency, I too trickle the last tenth and verify on another digital scale... since then, all my troubles have went away and I have full confidence in my reloads.
 
#8
As much as I would like to worry about Es and sd I just don't. The target tends to tell me much more then a chrono ever could. I'm not seeing vertical at distance out to 1k that I could discern to be because I let the charge master do it's thing. I've had great results with my charge masters and you simply have to believe the bullet. If I was shooting a different discipline light fclass or bench where the results may be more prominent then I would possibly trickle up or something. At this point using the charge master with couple tweaks has suited me just fine.
 
#9
I use one and my SDs are in the single digits I load 44.2 gr Varget and once you put a straw in the tube my over/under dropped to 1 or 2 rounds for every 50, and then only by a tenth of a grain.
 
#11
I believe the RCBS CM is spec'd for +- .1gr. That's pretty tight.

Tip - when it reaches your load and beeps wait for the round count to display and then switch back to weight. Often it will drop a couple grains and hit your load, beep, but not show the extra weight. When it comes back to the scale you'll have a true weight. It's never light, always heavy. On mine (41.8gr) I've seen 41.9-42, Easy to pinch a couple flecks out to get the right weight.
 
#12
StampCreek said:
I believe the RCBS CM is spec'd for +- .1gr. That's pretty tight.

Tip - when it reaches your load and beeps wait for the round count to display and then switch back to weight. Often it will drop a couple grains and hit your load, beep, but not show the extra weight. When it comes back to the scale you'll have a true weight. It's never light, always heavy. On mine (41.8gr) I've seen 41.9-42, Easy to pinch a couple flecks out to get the right weight.
Click to expand...

This bugs the crap out of me, but I do the same thing. It lies on the initial beep, and only shows the true value later. I've gotten pretty good at picking out .1 or .2 grains of powder.
 
#14
Killswitch Engage said:
As much as I would like to worry about Es and sd I just don't. The target tends to tell me much more then a chrono ever could. I'm not seeing vertical at distance out to 1k that I could discern to be because I let the charge master do it's thing. I've had great results with my charge masters and you simply have to believe the bullet. If I was shooting a different discipline light fclass or bench where the results may be more prominent then I would possibly trickle up or something. At this point using the charge master with couple tweaks has suited me just fine.
Click to expand...

Wise words spoken here. I totally agree. I believe that a lot of shooters gets all wrapped up in results that have little bearing of the ultimate outcome of the shot. Also something to consider, how accurate is the chronograph? Unless you spend a boat load of money, you will not get to within 2% of the actual velocity of the bullet traveling over the chronograph. Think about it: 2% of 2700 fps is 54 fps. Sounds a lot like the SD that I see thrown around in this thread. Speedometers on cars are the same way. The faster the speed, the greater the likelihood of error. And when you measure propagation of error, they multiply. So really, how can you measure SD in the 5-10fps range? You cannot.

I love it when Mr. Killswitch said "trust the bullet".
 
#19
Drifter™;3116446 said:
I didn't realize that people actually use the CM without disabling the annoying beep.
Click to expand...

That reminds me - does anyone have a link to a comprehensive CM reprograming guide online? I googled and found only random forum posts. Is there anything better out there? The instructions had nothing (which I can understand - if I were in RCBS's shoes, I'm not sure I'd be encouraging people to dick up their units either).
 
#20
Drifter™;3116446 said:
I didn't realize that people actually use the CM without disabling the annoying beep.
Click to expand...
It's easy for me. I just leave my hearing aids out when I am using the CM. :)

I know this is going to sound really anal but, after wondering about CM accuracy myself, I experimented with just how wide the variance can be. Nothing scientific but just to satisfy my mind. If the CM threw a tenth over I would remove one granule at a time with tweezers until the readout showed my correct charge. Usually two or three granules. Then I got to thinking "just how many granules can come off after that before I go one tenth low. With Varget or H4350 (my two main powders) it was about four to five more granules. So there is variation between charges that read out as what you are trying to throw. I quit worrying because I didn't see any difference in SD or AD when I went from my old method to the CM. I have one load that is down to 2 FPS SD. Now I own two CM and rarely use any other powder measuring method. I had rather be shooting than measuring powder by the granule.
Edit:
I used one of the You Tube videos to reprogram both of mine and, (even before then) use the straw mod. They run much faster and I get an "over" about two in every 100 rounds.
 
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#21
From another board

Rcbs sent me a email on how to speed up the chargemaster.
If any one wants the info. pm me your email and I'll foward it
to you.
This is right from RCBS:

Chargemaster 1500 Speed Adjustment

1. Turn the unit on.
2. When 0.0gn is on the display, press BOTH the ENTER and the EDIT MEM keys on the dispenser at the same time. Hold for a second and then release. If done properly ADJUST PARAMETER should scroll across the display followed by HSP 00015.68 (This number represents the number of grains away from your entered charge when the tube will shift from fast speed to medium speed. That is at 15.68 gn from your target charge the dispenser will shift from fast to medium speed.) To speed up the unit, this number needs to be decreased and to slow down the unit, this number needs to be increased. (On a slow unit, I would change this number to11.00 gn this is done by pressing the following keys: 1 1 0 0 ENTER (pressing the enter key sets that value and moves to next setting in program in this case, to medium speed to slow speed setting)
3. HSP 00003.42 should scroll across the display now. This number represents where the unit will shift from medium to slow speed. Using the same process as before in # 2. For a slow unit I would change this number to 2.50 gn this is done by pressing the following keys: 2 5 0 ENTER (pressing the enter key sets that value and moves to next setting in program in this case, to slow speed to trickle speed setting)
4. HSP 00001.08 should now scroll across the screen. This number represents where the unit will shift from slow speed to trickle. Using the same process as before in # 2. For a slow unit I would change this number to .90 gn this is done by pressing the following keys: 9 0 ENTER
5. This is all the adjustment that needs to be done to the unit. You need to press the ENTER key to cycle through the rest of the program. (approx. 22 times) The unit will start its normal initial countdown process when this is done. You need to test out the dispenser now. Enter your target charge and dispense. I usually disregard the first charge. Throw a few charges at these settings to see if they will work for you. If they don’t, return to step # 2 and repeat the process. NOTE due to powder variations you may have to adjust the unit for each powder. If you have any questions about this matter please call our customer service line 800-533-5000 my name is Don Legg and I am more than happy to answer any questions you may have.
 
#22
I have been using a CM for about 5 years now.

Initially, I just went with what it was showing on the display at the end of a throw, which per above is not always going to be the desired charge entered, it will over and under throw periodically. In those cases I would just adjust to the desired charge by adding or removing kernels by hand.

Overall this worked very well, it was fairly quick and simple. As you will learn, some powders will throw much more consistently than others, and yes the "McDonalds Straw Upgrade" helps (not sure why RCBS doesn't do something to fix this other than tell you to add the straw?).

During my load workups, the numbers on the Chronograph looked good. Most of my distance shooting was on steel, and I was happy with the results.

I then started doing a lot more paper shooting at distance, and was not 100% happy with my results, so I started looking at the "devil being the details". I was curios how "accurate" the RCBS charges really were, since that could be a factor, so I started using a secondary scale (GemPro 250 Digital Scale Review within AccurateShooter.com) to check them. What I learned is that there can easily be an error of 0.1-0.2 grains within some of the RCBS charge weights.

I am sure that there are a number of reasons why this happens with the RCBS scale to include sensitivity, response time, and drift.

Based on that discovery, if I am looking for absolute accuracy in the powder charges and I am striving for sub MOA ammo, I will throw them with the RCBS, and then check/correct them by hand with the GemPro.

For the ammo that I am OK with a 1 MOA performance level, I just throw them with the RCBS and load them.

Per above, a powder weight variation of 0.1 grains may not actually produce a measurable variation in performance/group size in all situations. If you are going to become "OCD" with your powder charges, it is best to make sure that investment will actually produce a measurable result on the target.

If you are going to run a RCBS, food for thought,
- Make sure your setup is 100%, solid level stable surface, no air currents, no strong electrical fields.
- They can be finicky when it comes to the environment, keep the humidity and temp the same when using them.
- Check it constantly and consistently with the reference weights, as you will see it can drift and will need to be re-calibrated.
- If you want to reduce the chances of error, once it is done throwing a charge, take the powder pan off of the scale, let it go back to zero and settle, then place the pan back on the scale and check the weight again. This is where/how you will catch a couple of kernels falling at the last millisecond and the scale not responding to them.
 
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#23
I have noticed that my Chargemaster is sometimes off by .1 grains when weighing my check weights (my RCBS set, not the 50 gram ones that come with the CM). My old Dillon D-terminator never is - it's always spot on. It's not enough error to make me stop using the CM, but I would be happier if they tightened it up a little. I do make sure I calibrate it every single time.
 
#24
damoncali said:
I have noticed that my Chargemaster is sometimes off by .1 grains when weighing my check weights (my RCBS set, not the 50 gram ones that come with the CM). My old Dillon D-terminator never is - it's always spot on. It's not enough error to make me stop using the CM, but I would be happier if they tightened it up a little. I do make sure I calibrate it every single time.
Click to expand...

Glad to hear you trust the Dillon digital scale. It is the ONLY thing I ever got with the Dillon name on it that just plain sucked for me.
 
#25
I find single digit SD and 1/2 moa capable loads can be thrown on the chargemaster. I played with my settings and have cut the the average throw time in about half, and don't use the straw mod. Every once in a while I'll get a .1gr overthrow, but it's rare. I also feel that even on the 600yd line I am not at any disadvantage over the guys that hand weigh everything on a beam scale.
 
#28
If it's off, my CM is usually +/-0.1gr either way. Which if you think about it, is only a 0.46% swing up/down (+/-0.23%) on a run-of-the-mill load of 43.0gr of anything. If the relationship between this infinitesimal amount were directly reflected in your velocity (doubtful), on a 105gr Hybrid being pushed by 43.0gr of H4350 going 3100-fps would mean you'd have +/-7-fps (14-fps total swing up/down) of variance. At 1000-yards for that load, according to exbal, your total vertical could be off as much as,... wait for it,... 2.8-inches!!! Even if the CM is 0.2gr off either way, the 'potential' effect would only be 5.5-inches MAX at 1000-yards. If you're shooting for group or score, then by all means, continue to trickle,... but if you're shooting at steel targets within 1000-yards,... I wouldn't sweat it. Powder charge accuracy is easy to achieve, but unfortunately, it's one of the least influential variables. Keep it in perspective.

Ry
 
#31
Same here roughly. With the 1010 and a trickler i can get 2 sd, sometimes even one sd. With the Chargemaster it is more around 3-5 sd, and when i'm lazy and dont throw the little overweighed charges back in, than they tend to grow a bit higher, but neveranything over 9.
For benchresting it might be more interesting to underthrow and then trickle to the wright amount, but for any other comps, just trust your CM, there are many other variables who will throw your rounds off with bigger numbers than these small difference in velocities.
 
#32
Like some, I was using the CM and throwing my charge .1 light and transferring to a beam and adding grains to finish it off. I decided to try loading a box of .223s with Varget using ONLY the CM to see what the results would be. I did check the CM throws with the beam scale 4-5 times but it was within a red CH so I felt confident that the loads were close to the 24.8 grains it was throwing. I had NO loads over or under my 24.8 grains programmed in the CM. At the range, groups were normal (5/8" or less) with an average of 2922 fps, an ES of 36 and SD of 10. Considering the time saved loading straight from the CM and the results at the range, I'll continue to load from the CM until something causes me to rethink the process.
 
#33
Today on the range i got these results with ammo loaded with just the CM, no trickling no fancy nuttin...just clean throws, only threw every overweight charge back in the pot;
308w
208amax behind 46gr of N550 touching the lands, first ten rounds:
1- 820mps
2- 809
3- 805
4- 812
5- 812
6- 804
7- 804
8- 804
9- 803
10- 813
Min 803
Max 820 (only the first cold barrel shot??)
Avg 808mps = 2651fps
Sd 5 (due to the first shot of 820)
Es 17

After that let it cool and shot another 15 shots;
1- 809
2- 814
3- 804
4- 813
5- 809
6- 809
7- 807
8- 807
9- 805
10- 811
11- 810
12- 811
13- 809
14- 812
15- 805
Min 804
Max 814
Avg 809 = 2654 fps
Sd 2
Es 10.

Maybe not good enough for benchrest, but for any discipline that goes long range under influence of baro and wind, more than sufficient, at least the smoothnand fast way of reloading outweighs by far the shitty work with a trickler.
 
#34
I have to admit that I do not worry about muzzle velocity except for a tactical rig where I am shooting at ranges beyond 600 and then I just use a ballistics solver to determine what it thinks the velocity is. I agree that is not the most accurate way to measure velocity it is a great way to tune the solver so it gets the most accurate come-ups, the more accurate the come-ups are the more accurate the rig is. On my F-class rigs I just zero them at the range I shoot them at, I usually only shoot at 1,000 (currently a 280 AI) and 600 yards (always a 6mmBR) and both guns are zero'ed and verified at those ranges. The absolute zero of the F-class guns is not as important as we get sighters.

How do I do my load development? I shoot ate either 100 or 200 yards to get candidate loads and then do my ladder tests at the intended range. After the ladder tests I will then shoot the the top two candidates at range a couple of times and compare the scores and vertical dispersion. The load with the lower vertical dispersion is usually the one I go with unless the other consistently out scores the other. Once the load development is done the F-class rigs are rarely shot other ranges.

Long Story Short: I think the scores/results tell you enough information to find the best shooting load for that gun and that discipline. Score and results could be group size if your discipline cores that way or scores from the target or whatever it is discipline dependent.
 
#35
True.
Especially in competitions where you have sighters, muzzle velocity is of less importance.
But for hunting or tactical comps where the first strike hit either on plates or animals is very important, knowing your V0 will be of great value.
But even if you did measure them, you still need to calibrate/ tune most ballistic solvers, even the more expensive ones like FFS, especially for long range.
And knowing your chargemaster does not give big ES in your loads, will make you more confident that it wont cause for any big differences in elevation between rounds.
 
#37
I'm new to reloading. I'm seeing a ES of 24 and an SD of 9 on my 75gr 223 loads using the Chargemaster.
Comparing that to the factory Hornady 123SST grendel ammo with an ES of 12 and SD of 5 has me convinced I need to be more consistent with neck tension.
 
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