Scale Report

B

Boyd Allen

Active member
Recently I was tempted by an ad that offered a RCBS 5-0-5 scale, (which, from the picture, appeared to be in decent shape) for $37 delivered to my door. I couldn't help myself, and so I made arrangements, and sent a check. After the time it took for the letter to arrive, and the package to come. I found that the picture had not lied, and that while it seemed to have sat out a bit, that all the functional parts were in excellent condition. Having tuned up a couple of other balances, I set about removing minor bits of rust on the non functional surfaces of the main knife edges, and sharpening and polishing them, polishing the agates, and working over the knife edges and wire hanger that support the pan holder. Then I adjusted the weights in the pan holder so that the tops of the agate retainers were level with the beam zeroed, and wrapped the leveling screw with a few turns of teflon tape, to take the wiggle out. After that, I played with the scale a bit, decided that it worked as I wished, and wrapped the beam swing limit stops with some thin soft adhesive backed foam. At that point I set the scale up with a manual focus webcam about an inch and a half away from the end of the beam, so that I could see the image on the monitor behind it, and did a little test. Opening a partially full jug of Varget, I poured a little into the cap, and after carefully zeroing the scale, dropped a single kernel of powder into the pan, which moved the beam half the width of the line that on the scale body, added another which made the misalignment easier to see, at the full width of the line, and continued on till I had added a total of five kernels to the scale pan, at which point I moved the tenth grain adjustment weight to the .1 gr. position, and the beam returned to zero. By my math, that means that I was able to see beam movement from the addition of .02 gr. to the pan. Not bad for $37. While in the process of playing with the scale, I solved another small mystery. It seems that with the TV on in my computer/reloading room, I cannot hear the air conditioner running, and that I did not at first understand the cause of a slightly erratic zeroing of the scale, nothing major, but it was there, but after I had finished the sensitivity test, It was there again, until I cupped my hands around the end of the beam and pan, at which point the scale returned to where I had set it. It seems that reducing friction and increasing sensitivity comes at a price. Wind currents now have to be considered. So there you have it. Reloading on a budget does not have to be imprecise. There is hope for long range shooters on a budget.
 
That is AWESOME!! I had no idea they could be set to be so sensitive..... and I'm familiar with sensitive......... someone barges into my reloading sanctum during a charging run and it'll screw the air up for minutes.

Good Job

(Plus this makes me happy because I just steered a friend to the RCBS scale for his setup)
 
Boyd,

It is nice to know how accurately these scales can be made to function, but...

Now we need to know the allowed variance in weight of a granule by the manufacturer.

Gunpowder is a way of storing energy, and we're interested in (1) the total amount of energy, and (2) the rate of it's release. As to (2): The size of the kernel matters. Some manufacturers, such as Bofors (they make the powder used in Alliant's Reloader line) actually mix granule sizes to get a specific burn rate. So when you add "just one more kernel," what have you really done?

& if it's not granule size, it's deterrent coating -- who can measure that?

If we really want to get down to even energy levels, we need a substance to store & release large amounts of energy very consistently (i.e., very evenly with respect to some measurement approach, weight or volume), so that energy & it's rate of release can be measured very accurately. Some liquid, I imagine.
 
Heck Charles, I was just having a little fun. I am not saying that the scale is as good as some fancy electronic scale, but that it is a lot better, and more sensitive than it was designed to be. If I really want to get crazy, I could get into its actual accuracy and linearity, but for my purposes, as long as it is consistent, and I work with the one scale, I think that I should be OK. I already had a 10-0-10 that I had tuned up, and I wanted some more experience, and to see how this design was to work with. I get tired of rolling one and tenth thing back and forth on the 10-0-10 every time I zero it, and then have to reset it to the weights that I work with for my PPC. I thought that simply moving the tenth and one grain adjustments on the beam might be more convenient, and at this point, it looks like I may have been right. In truth, I throw most of my charges and shoot them at 100 yards. I have spent considerable time learning the ins and outs of measure operation, and while I may add checking the weight of what I am throwing to my routine, I doubt that I will ever weigh all of my charges, given the consistency that I have been able to throw them to, and the distance that I shoot. The reason that I wrote about this little exercise was that I thought that the information might be of interest to someone who is a little frustrated with his balance's performance, and give some hope to shooters that, like me, are on a budget, but still want to make things as good as they can.
 
Heck Boyd, I think what you've shown is that little scale is, for shooting purposes, as good as one can get -- and maybe better than one can make use of, given how powder is manufactured. That was (suppose to be) kind of my point...
 
Thanks for the clarification. I wasn't sure what your point was, but was glad that you noticed my little report.
 
Charles E said:
Boyd,

It is nice to know how accurately these scales can be made to function, but...

Now we need to know the allowed variance in weight of a granule by the manufacturer.

Gunpowder is a way of storing energy, and we're interested in (1) the total amount of energy, and (2) the rate of it's release. As to (2): The size of the kernel matters. Some manufacturers, such as Bofors (they make the powder used in Alliant's Reloader line) actually mix granule sizes to get a specific burn rate. So when you add "just one more kernel," what have you really done?

& if it's not granule size, it's deterrent coating -- who can measure that?

If we really want to get down to even energy levels, we need a substance to store & release large amounts of energy very consistently (i.e., very evenly with respect to some measurement approach, weight or volume), so that energy & it's rate of release can be measured very accurately. Some liquid, I imagine.
Click to expand...


Here's the thing...... I CAN and I DO easily get ES down in the single digits weighing to the kernel.

CAN and DO

speculation is moot IMO, Mission Accomplished,
for me anyway,
:)
al
 
Boyd,
Nice summary on tuning the scale. I had not thought of "wrapped the leveling screw with a few turns of teflon tape, to take the wiggle out."

I have a lot of experience with quality lab balances that weigh to 0.1 mg. Our Lab balances are on 24-7 and still there's some drift to the measurement. With the way we typically use scales for reloading - turn them on, tare, adjust a powder measure, turn off - I think we are better off with gravity balance than an electronic one. A tuned gravity balance is certainly precise enough & gravity doesn't drift.

Regards,
Ron
 
alinwa said:
Here's the thing...... I CAN and I DO easily get ES down in the single digits weighing to the kernel.

CAN and DO

speculation is moot IMO, Mission Accomplished,
for me anyway,
:)
al
Click to expand...
Well, you'er one of the lucky ones.

Here's one example. I know of many more... Steve Shelp, a very good 1K shooter who went to a .338 some years back, first tried N-170. He got very low ES/SD for velocity -- single digit, just like you. But his groups weren't as good as with H-1000. Problem was, the ES/SD with H-1000 was in the 20+ fps region.

Now, his mission was winning matches, so finally, reluctantly, he went with H-1000. Yes, you can tune out most of the vertical (the portion that's due to velocity variations). But that variation in velocity effects wind drift a bit, too. Just not as much (arithmetic rather than geometric progression).

Sadly, success isn't as simple as weighing to the nearest kernel Al.
 
Charles E said:
Well, you'er one of the lucky ones.

Here's one example. I know of many more... Steve Shelp, a very good 1K shooter who went to a .338 some years back, first tried N-170. He got very low ES/SD for velocity -- single digit, just like you. But his groups weren't as good as with H-1000. Problem was, the ES/SD with H-1000 was in the 20+ fps region.

Now, his mission was winning matches, so finally, reluctantly, he went with H-1000. Yes, you can tune out most of the vertical (the portion that's due to velocity variations). But that variation in velocity effects wind drift a bit, too. Just not as much (arithmetic rather than geometric progression).

Sadly, success isn't as simple as weighing to the nearest kernel Al.
Click to expand...

I guess I misunderstood the focus of this discussion...... I didn't know we were talking about "success" defined as "winning," you were talking about energy levels....

You contend that there are variables beyond our control like kernel size, deterrent coating variation etc which make weighing to the kernel of powder less than efficacious.

I contend that I load 20 cartridges from 6PPC thru the various magnums to 338 Lapua and achieve consistently low ES numbers within usable velocity ranges.



al
 
I contend that I load 20 cartridges from 6PPC thru the various magnums to 338 Lapua and achieve consistently low ES numbers within usable velocity ranges.
Click to expand...

I believe you. In fact, I believe that I can do the same. Here's the rub. Given that load, can I come up with another load -- probably different powder, but not necessarily -- that shoots better? And what I'm suggesting is, yes, as often as not.

Now if I'm going to go shooting, competitively, which load am I going to shoot? And of course, it is the one that groups best/scores highest.

Even if I can't get the velocity variation down.

What I'm further suggesting is that I often have the most trouble with the Reloader series of powders. Really small groups, except...

Now the Reloader 22 and 25 I most use, have quite different sizes of granules, even within a single 1-pound jug. So, do two larger granules weigh as much as three smaller ones? Sometimes. Is the energy the same between two large and three small? I have no idea. Likely not, esp. in the matter of the rate the energy is released (how "fast" or "slow" those granules of powder are).

So if I'm just blindly hitting a weight and the energy content can vary, what have I done? I have a load that likely wont have as narrow an E.S. as one with another powder. But suppose it shoots better? Often the case with Rel-22 and 25.

* * *

Steve's situation was a good one to illustrate things, esp. since it wasn't with those oddball Reloader powders. Plain old single-base, conservative powders can & do exhibit the characteristic. Those who know Steve know he's been shooting long range for over 20 years, first at Williamsport, later at Hawks Ridge. When he tests, it's not one or two five-shot groups & a quick conclusion. He's an ex works-for-a-living Marine, who now makes his living in the telecommunications field. (Sadly, he's fallen in love with driving racing cars & isn't shooting at all, but I figure he'll come back.) In short, you an take what he finds and reports to the bank.
 
Comparison between oil, magnetic, and non-dampened beam scales

Boyd, Have you done any comparison between the above types and which do you like?
Centerfire
 
I have not. I really have no complaint with magnetic damping. It seems to work pretty well. Some fellows who do not fully understand how it works, that the damping is proportional to the speed with which the beam moves, seem to think that there is a problem with the magnets causing the scale to be less sensitive, but I do not think that they do, since when the beam is at rest, no eddy currents are being generated to interact with the magnets. IMO the main (but not only) issue is friction at the knife edges, and sharpening these, carefully, is the key.
 
Sharpening edges

Thanks Boyd. Regarding the edges. Mine are blued and therefore I thought they might be hardened.
I suppose you are just using a file?
Centerfire
 
They are not all that hard, and I would never use a file...too coarse. I have used either a diamond lap, or some very fine wet and dry wrapped around something flat that I can maneuver. I also do a little deburring after the sharpening. Magnification helps a lot. Also remove the agates and clean them and the area that they rest in. Take your time and work carefully.
 
You must log in or register to reply here.
Back
Top