RCBS chargemaster Lite arrived today!

[Catch-22]

Whoops, double post!

[Catch-22]

Hi all,

 

So i've spent a couple of hours this afternoon testing the accuracy of the new Chargemaster Lite against my fantastic GemPro 250. Very very interesting and it's better than i'd expected it would be, but right on what I hoped it would be.

 

Really I wanted to test two things;

• How accurately can it throw a charge & detect it as accurate
• How accurate is the load balancer - can it detect if I carefully trickle up to a given weight.

Knowing answers to the above would hopefully determine how well the throwing mechanism works and also if the 0.1grain claim by RCBS is correct or not.

 

Results summary;

The load balancer on the CM Lite is really very accurate, more so than RCBS claim. My results show that it'll consistently detect and hold to within a maximum of 0.04gn - in most instances it was better!. The GemPro detects 0.02gn, so I'm very happy to accept 0.04gn!

However, to get this accuracy you MUST throw a light charge (0.1gn under), MUST remove the pan from the scale, replace it and ONLY THEN trickle up to your given weight. If you don't remove and then replace the pan on the scale before trickling, the CM Lite has difficulty in picking up the small changes in charge weight.

Directly throwing charges really does vary in result. By observing it throw charges, it seems that the accuracy depends on which powder you use. Sometimes the smaller and less dense kernels (N140) will trickle out too easily when the machine is doing its final trickle up to the specified charge. Many people used the MacDonalds straw trick on the only 1500 model and maybe it would help here too.

 

In answer to my two questions above;

• I think the CM Lite is so so at directly throwing a charge accurately. I think for some people, being a 10th of a grain or two out is fine. For accurate, long distance shooting, no it's not good enough to just throw a charge and dump into the case. Again, modifying the spout or using different powders might give different results, but for me I won't be just throwing charges directly into cases!
• I think the load balancer is actually very very accurate. I'm confident in it's ability to detect minor changes in charge weight BUT ONLY if you remove the pan, replace and then trickle up.

Something else to note is the CM Lite never told me it 'overthrew' a charge. However there were one or two occasions where I saw quite a few kernels tip out in the last trickle. The CM Lite said it was at the specified weight but when I removed the pan and replaced it again, it then recalculated and said it was high. And if you look at the numbers below, the CM Lite overthrew EVERY charge.

Again, I believe this backs up my findings that the load balancer needs the pan to be removed and replaced again to tell you a more accurate answer.

 

 

Test rules;

 

Following some inspiration from a YouTube video by Eric Cortina (worth a watch actually) on how he trickles up to weight using his CM 1500, I devised a similar but more detailed test plan for the CM Lite.

• Both CM Lite & GemPro had been left 'on' for 48hrs to allow the circuitry to be warmed up
• Room was insulated as best as possible to mitigate 'wind drift'
• Other electrical devices in the room were turned off (including my mobile) to reduce electromagnetic field effects
• I sat away from bench to minimise vibrations and me breathing on the scales
• GemPro would validate charges with it's wind shield down, again to minimise drift
• Both CM Lite & GemPro sat next to each other and would be re-leveled, turned off, back on and re-calibrated between switching powders to make it as fair as possible
• I would test 3 different powders; Vhit N140, Lovex SO70 and VARGET. Nice thing was the powders have different densities and cut size to test
• Desired charge weight was 38.6gn - as this is the charge I use in my rifle
• When 'trickling up' I used a pair of tweezers and dropped individual kernels into the pan, waiting several seconds between each kernel to allow time for the scale to stabilise (yes...it was laborious!)

Test Plan;

• CM Lite to throw 38.6gn. Check charge on GemPro and log results (repeat 5 times)
• CM Lite to throw 38.5gn. Trickle up to 38.6gn dropping individual kernels to pan. Check charge on GemPro and log results (repeat 5 times)
• CM Lite to throw 38.5gn. Remove pan from scale, wait to stabilise and replace pan again. Trickle up to 38.6gn dropping individual kernels to pan. Check on GemPro and log results (repeat 3 times - I simply couldn't be bothered to do more!)
• Repeat steps 1-3 for each powder in turn
• Calculate ES across charges and work out how 'off' the CM Lite might be from the desired charge

Results;

 

N140

• ​Throw 38.6gn. Results = 38.74 // 38.68 // 38.78 // 38.64 // 38.68 (ES 0.14gn, max 0.18 OVER weight)
• Throw 38.5gn, trickle up to 38.6gn. Results = 38.70 // 38.70 // 38.68 // 38.68 // 38.68 (ES 0.02, max 0.10 OVER weight)
• Throw 38.5gn, remove & replace pan, trickle up to 38.6gn. Results = 38.62 // 38.62 // 38.62 (ES 0.00, max 0.02 OVER weight)

SO70

• ​Throw 38.6gn. Results = 38.76 // 38.76 // 38.84 // 38.80 // 38.80 (ES 0.08gn, max 0.2 OVER weight)
• Throw 38.5gn, trickle up to 38.6gn. Results = 38.72 // 38.72 // 38.70 // 38.68 // 38.70 (ES 0.04, max 0.12 OVER weight)
• Throw 38.5gn, remove & replace pan, trickle up to 38.6gn. Results = 38.60 // 38.62 // 38.58 (ES 0.04, max 0.02 OVER & UNDER weight)

VARGET

• ​Throw 38.6gn. Results = 38.64 // 38.60 // 38.56 // 38.66 // 38.60 (ES 0.10gn, max 0.16 OVER weight)
• Throw 38.5gn, trickle up to 38.6gn. Results = 38.66 // 38.60 // 38.66 // 38.62 // 38.66 (ES 0.04, max 0.06 OVER weight)
• Throw 38.5gn, remove & replace pan, trickle up to 38.6gn. Results = 38.62 // 38.64 // 38.62 (ES 0.02, max 0.04 OVER weight)

I've been contacted by a couple of forum members who are awaiting their CM Lite's to come through too. If they get time, it might be helpful for them to run a similar test to validate my results.

 

But on the face of it, by taking the pan off and on again, then trickling up, I get variances of no more than 0.04gn in my charges. I mostly use N140 and my results show that I can get an ES of 0.00gn, with them being only 0.02gn over desired charge weight...consistently. Happy days!

 

Hope this helps you guys out.

 

Cheers,

Kon

[Malinois]

A super write up. Looking forward to mine landing.

 

 

 

Ian

[Catch-22]

A super write up. Looking forward to mine landing.

Ian

Hi Ian,

 

I've never owned an auto trickler before but I've been impressed with the CM Lite.

Yes it's got some quirks that one has to understand. And yes, removing and replacing the pan, then trickling up isn't quite as straight forward as just throwing a charge and being done with it. But all told, it's super simple, quick to use, and just about as accurate as my GemPro 250.

Even when doing the extra steps, it's still super quick & efficient. And I won't be going back!

 

Enjoy!

[Malinois]

I've only used the Target Master. It's good but I think mine is an early version and can be a bugger to setup.

 

The supplier ended up refusing my order to be sen to a forward shipping company so I have had to go through normal channels but I'm sure it will be worth the wait.

 

Ian

[Catch-22]

Actually, I did own a Target Master too - sold it here recently before getting the CM Lite. I just meant I didn't have one of these all in one auto trickler types ?

I liked the TM but the issue for me was setup time (as you also noted) and just waiting for the balance beams to settle, then trickling up. This prompted me to get the GemPro - to use the TM to throw, and GemPro to validate/trickle up. Both setups were very accurate but felt it took too long to load 100 rounds. I'm confident my CM Lite has that problem solved and keeps the accuracy!

 

Bad luck about the shipping. When yours does land, I'm sure you'll be most happy.

 

Cheers

[22lrman]

Great write up. Many thanks for this as I was just about to buy one, and this confirms it will be a good buy.

Just one thing, could you confirm if has the adjustable speed settings like the 1500. (Fast, medium, trickle thresholds)?

And what was your overall dispense time, for the N140 charge for example.

 

Again many thanks.

[PhilM]

Seconded, great review Catch-22. I ordered one yesterday off the back of the review (that and my missus tiring of dispensing me charges manually with a thrower and trickler with my current electronic scales).

[Catch-22]

Great - glad it's helped!

 

@22lrman - so the CM Lite does have fast, medium & trickle built in but I'm unaware of any way (official or hacked) to adjust the timings at which they kick in. I think the units too new to know. Or it can't be done. Not sure.

 

One thing to reiterate in my findings is regardless of how well it trickled or dispensed, even if you do it kernel by kernel, by not first removing the pan then trickling up that final 0.1grain to your desired weight, the load balancer just won't detect (or display?) the charge accurately. So for me, changing the throw speed means nothing really. I'm content for it to do its thing, however quickly, to 0.1grain under weight. Then it's up to me to remove, stabilise and replace the pan before trickling up to the final weight.

I hope that makes sense!

 

In terms of how long it took to dispense 38.6grain N140...I dunno exactly. I didn't time it unfortunately. Maybe less than 10 seconds?!? But I didn't think it took too long at all. I didn't feel at any time like I was clock watching or getting impatient (I am quick to impatience at times), so for me I'm happy. Put another way, it's way less time, even with the slight faff or removing, replacing pan & trickling, than it ever took with my balance beam or digi scales. Plus I have my hands free to get the next case lined up etc.

 

One slightly annoying thing is there's no way (as far as I can tell) to mute the 'beep'. I've never owned the original CM1500 but from watching numerous YouTube vids on them, I think the 'beep' on the CM Lite is quieter and a bit less aggressive/annoying. Saying that, if someone works out a way to mute it, I'll do it!

 

Hope that helps!

[Foxshooter]

With my old CM when the charge has finished dispensing you get an audible beep and the number of charges/count is displayed. This then reverts to the actual weight dispensed. Its at this point I see if there has been an overcharge or the weight is what it should be. I've never seen an undercharge

 

Mark

[Catch-22]

Resurrecting this thread.

 

Has anyone with a CM Lite managed to validate my findings at all?

 

It would be interesting to see if peoples experiences with the strain gauge, and it's feedback, has been the same as mine.

 

Cheers

[Ralpharama]

I have picked up on this thread from a link on mine. I have now had the chance to put my CM Lite through its paces. It seems great.

I have re-weighed lots of loads but have found them all to be spot on. Occasionally on the very first load, when re-weighed, it is 0.1 under, but after that I have not had one single load that has weighed anything other than 100% accurate, presuming it weighs correctly in the first place. I haven't got a more accurate scale to compare with.

 

I have found that using Unique flake powder with 6.0 gr loads for my .357 is somewhat slow than my ability to complete the rest of the process leaving me to wait for it. Using the 45.5gr of RS52 for .308 is lightening in comparison, so speed seems to vary on powder type.

[No i deer]

It would be nice when someone actually makes one that is 100 percent accurate without throwing  a charge first then trickling up or taking it off and on etc.i am definately leaning more to one of these type despencer as I don' think I am benefiting using the gempro 250 to for the type of shooting I do.cant say for sure though..!

[Catch-22]

7 hours ago, No i deer said:

It would be nice when someone actually makes one that is 100 percent accurate without throwing  a charge first then trickling up or taking it off and on etc.i am definately leaning more to one of these type despencer as I don' think I am benefiting using the gempro 250 to for the type of shooting I do.cant say for sure though..!

The closest I've found is the Autotrickler and Autothrower system, which when combined with a Satorious or A&D scale, delivers loads to within 0.02gn (as good as I've been able to do with the CM Lite) but without any need for trickling up and only takes 10 seconds per measure. 

Looks great and would be really fab to use but its a step up financially - about £800 for the whole package, including scale, whereas the CM Lite is just short of £400 new in the UK.

[No i deer]

Velocity wise what does 0.1grs mean in fps just as an average approximately.if you can despence 0.02grs consistently that sounds about as good as it gets then.0.02grs is about 1 kernal.i loaded some up last night with the gempro 250.It's slow but sure.occasionally I take the pan off and put it back on.0.02gr seems about it's variation.quite often it's bang on.

[Reloader54]

19 minutes ago, No i deer said:

Velocity wise what does 0.1grs mean in fps just as an average approximately.if you can despence 0.02grs consistently that sounds about as good as it gets then.0.02grs is about 1 kernal.i loaded some up last night with the gempro 250.It's slow but sure.occasionally I take the pan off and put it back on.0.02gr seems about it's variation.quite often it's bang on.

lots to affect an answer  is my guess, calibre,powder, bullet,case variation,ect,ect, you can overthink it almost to the ridiculous. 

you could cut a batch of kernals in half and just use them to balance the loads, or even count individual kernals I'll wager there would still be the odd "flyer"  

I love reloading and I take my time and enjoy everything about it, but its good to get plenty "trigger time" too.

[Catch-22]

56 minutes ago, No i deer said:

Velocity wise what does 0.1grs mean in fps just as an average approximately.if you can despence 0.02grs consistently that sounds about as good as it gets then.0.02grs is about 1 kernal.i loaded some up last night with the gempro 250.It's slow but sure.occasionally I take the pan off and put it back on.0.02gr seems about it's variation.quite often it's bang on.

Yes it's a tricky one to answer. Different powders have different energy ratings, so one powder will give more uumph than another. Then you've got to consider not all kernels of the same powder are identical. Barrel length and even the tightness of the bore will affect pressure developed in pushing the bullet to the target. Bullet weight is another factor, lighter bullets need less effort than heavier ones. 

However, if you think each kernel of say VARGET could be around 1-2fps depending on the variances noted above. So if a kernel of VARGET is about 0.02gn, a variance of around 0.1gn between charges could be around 10fps. 

Below is taken from the Autotrickler website as he's a lot smarter than I am and does a good job of explaining how to translate the affect of accurate powder measuring into best case target scenarios.

"Note that if you operate the A&D scale in units of grains, it reports in divisions of 0.02 grains. That is actually 1.3 milligrams, so it is slightly less precise. However, this is still less than the weight of a single kernel of Varget.

Let's relate powder weight to muzzle velocity. I will use my competition load as a reference: 308 caliber, 185 grain bullet, 30 inch barrel, with 44 grains of Varget. The muzzle velocity is 2750 fps. The relationship between powder and muzzle velocity is 50 fps / grain. It may vary from 35 to 100 for larger or small cases but 50 is a good working estimate.

That equates to 0.77 fps per milligram. This means if I add one more kernel of Varget it will increase my muzzle velocity by 1.16 fps. 

Now we can relate muzzle velocity to elevation at long range. For my load at 1000 yards, ballistics calculators tell us the relationship between muzzle velocity and elevation is 0.03 moa / fps. That means that one extra kernel of Varget would put that bullet 0.035 moa higher on paper.

Now lets set up three scenarios for comparison: (using fictional characters that bear no resemblance to actual people!)

• Mr. Speedy would have us accept any charge within +/- 0.02 grains 95% of the time. This is how I recommend to use the autotrickler, because it will finish within this range most of the time and requires little effort from the user. Working in the unit system you are familiar with means you are less likely to make a mistake.
• Mr. Careful adds or removes a kernel by hand until the scale reports exactly the right number in milligrams. This is the best possible with the A&D scale, and what I'm sure many of us do to prepare for a national championship.
• Mr. Perfect settles for nothing less than absolute perfection. He reloads in an underground clean room and his powder charges have a weight error of exactly zero.

If the measurement of the powder charge was the only factor that goes into the muzzle velocity variation of a load, then we would all be firing one-hole groups at 1000 yards. There are other random errors at play, most notably the combustion process itself.

We have to choose a value for "everything else", and we have to work in terms of standard deviation (not extreme spread) because we are talking about normally distributed random error. The SD of a well-developed load might be around 4, so let's use this as the example.

This is the point of confusion for most. How do you combine two independent error sources? They do not just add together. This is a key point to understand when applying statistics to shooting.

To illustrate the concept, I like to use a chronograph as an example. Suppose your chronograph has an inherent error SD of 0.1%, which is 2.75 fps. Now you would like to measure your ammo which actually has a true SD of 4 fps. Well, whether you like it or not, if you fired enough shots and measured the SD of what you get, it will not be 4. It will not be 6.75 either. You will get an SD of (drumroll please...) sqrt(4 x 4 + 2.75 x 2.75) = 4.85. Sometimes your chrono reads high when your bullet is slow. Sometimes your bullet is fast but the chrono reads low. When all is said and done, you get the square root of the sum of the squares.

So now back to our three scenarios. For the purpose of converting our weighing strategies into SD, we divide the total range by 4. Because for a normal random variable, 95% of samples are within +/- 2 SD.

Mr. Speedy is okay with +/- 0.02 grains which means an SD of 0.01 grains. This is an SD of 0.5 fps. Combining that with our 'everything else' SD of 4 produces a load with an SD of 4.031 fps.

Mr. Careful applies a little extra effort to weigh to an SD of 0.25 milligrams, which is 0.19 fps. This produces a load with an SD of 4.005 fps.

Mr. Perfect magically produces ammo with an SD of 4.000.

Now how does this relate to elevation on target? Well, for each of these loads, fired perfectly from a machine rest in completely still conditions:

• Mr. Speedy: 95% of shots will fall within 0.4837 moa.
• Mr. Careful: 95% of shots will fall within 0.4806 moa.
• Mr. Perfect: 95% of shots will fall within 0.4800 moa.

The difference between these spreads is less than 1 millimeter at 1000 yards. Consider how much we struggle to keep the bullets within a 1 moa circle in match conditions. If you add all the other error sources like aiming, mirage, wind, and the gremlins, you can work out mathematically how little that last kernel really means.
 

[Reloader54]

"see,,, just as I said"  but not as concise.

[No i deer]

Thanks for that.thats put some real perspective on things.i will keep doing what I am as I am not a milligram away from perfection then .My reloading is better than my shooting me thinks .

There is also someone who is as knowledgeable as Laurie 

[Malinois]

That is a fantastic reply

 

[Ralpharama]

That was a really interesting explanation.

Me, I am competing with no one, save myself and within 0.1 grain is fine. In my experience, the vagaries of winds at 1000yards make a shed load more error than a few minute fractions of an MOA caused by a kernel or two up or down in a load.

I was on a 600metre range (Rogiet Moor) yesterday and we all found that as the wind blew a bit stronger it could shift the bullet as much as half a milli-radian, and it was far from being a windy day and at least it was more or less in the same direction unlike Warminster IR2 when it changes direction all the time. 

My load chucks the bullet (157gr Lapua Scenar) out the barrel (.308 STR) at 2905FPS which means it'll still be super sonic when it arrives at the target 1000yards away. I use 45.5 grs of RS52. It seems that this is pretty much as hot a load as it safe from the research I have done. I feel any more would put unnecessary wear on the barrel anyway. 

I feel that the CM Lite probably reduces the errors in my loads sufficiency to make the weak point in my accuracy being my shooting and experience rather than the ammo.