beam scale repeatability question...

I do know that 1/10 of a grain can give dramatic results when your load hits a node of a rifle barrel. I have shot enough ladder tests to know that. I have also read that many other things affect the accuracy of a rifle cartridge. Case volume and neck tension etc etc , etc, to name a few.

In my opinion the weight of a powder charge is a very good way to deliver the exact propellant charge. I doubt that the density of individual powder grains vary to any degree so that weight will always give you the best estimate of the amount of propellant in your case.
That being said.. If you have your powder measure that you have tweeked so that it delivers the same charge everything based on volume i would suggest you weigh the charges and you will find they are very close in weight. Not all powder measures are created equal i would think as my Dillon 550 throws +/- 1/10 of a grain.. so if you weigh the lightest and the heaviest they will differ by 2/10 ths of a grain. Not really a problem with pistol rounds but could have dramatic consequences in a rifle round tuned for a specific barrel node. I have seen it happen in a match..

So while some have great skill with a specific powder measure producing incredible reproducibility i still choose to weigh my powder charges to ensure that is not the limiting factor when i trying to shoot 1000 yards and hit a 5 inch circle (VBULL).

RDG
 
BattleRife said:
I have an Ohaus 505-10 scale that does this if the beam has wandered to one side or the other, so that one end or the other of the pivot edges rubs against the housing. It's fairly noticeable as it causes the scale to be out probably 0.02grams, or ten times what you are experiencing. I have never noticed any problems if the knife edges are centered on the agate block. Above all, I agree that it is an academic pursuit only, 1.5 mg is bugger-all in practial terms.
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I have the ohaus scale that RCBS sold, and I was not happy with how it was working, so I called RCBS, and they told me where to send it to. I paid the postage there, and they paid to ship it back, it was much better. It was not a new scale when I bought it.
 
Ducimus said:
So I've got a Dillon beam scale. I zero it before use. There are no drafts around. I check for a level surface before use with a bubble and shim the legs of the scale as necessary. The pivot points are clean.

After I zero the scale if I give the beam a tap it doesn't always return to zero. It could end up a little high or low. I re-zero and tap the beam and again it doesn't return to zero. Now the amount it is off is approximately the weight 2 sticks of Varget. Is this normal or is there a problem?
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I don't use Varget, but with my 700X, 800X, Titegroup, 231, Bullseye, 2400 and Universal powders, I havent experienced any variations or problems with calibration with my RCBS 505 scale. When I empty the little powder dish, it always returns to proper zero. This RCBS 505 is 22 yrs old.

I have a Dillon scale that a buddy uses now, so I cannot check its consistency but I remember back when I used it, it was every bit as good as the RCBS.

So yes, I'd say there is a slight problem with your Dillon. Check the knife edge pivot of the balance beam as well as the notch it rides on. There might be tiny specks of sand or dirt that causes the very, very, slight erratic behavior. Perhaps a paint brush and some Varsol to clean the pivot notch will help. Two grains of even large powder grains like Varget is really miniscule, IMO.

Good quality beam scales like the Dillon and RCBS are very accurate and consistent.
 
The fact that your scale is only accurate to +/- .1gr (read +/- 4-5 kernels of varget) I would say it is doing exactly as advertised and working perfectly.
 
Well I picked up a Lyman 55 today. We'll see how well it dispences. I may just throw the charges as is or just under and trickle up. Judging from the posts here I guess my scale is good to go.
 
On my old Ohaus i will clean the knife edges and seats with a cotton swab and alcohol if it`s getting sticky or slow. then use the calibration weights to check it.
 
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