Scale linearity?

[mousegunner]

I noticed that my 505 is not linear. I keep it clean and covered so it's not exposed to dirt or rough handling.

I've balanced the scale and used my check weights and individually each weight is correct. When I combine them to 55.5 grains it's just a hair off. About the thickness of the line on the scale.

I then used a 55 FMJ and it comes it at 55. A Nosler 77 comes in at 77 grains. I had weighed these some time back and kept them for check weights since they came in right at the numbers.

So, I mostly load .223, .308, 9mm and .45 so I'm not loading heavy powder weights. If the scale is off at heavier weights I don't use does it matter that it's slightly off?

I am going to rebalance it, clean it again and adjust the weights in the pan. Hopefully I can get rid of the slight variance. Anywho thanks for looking.

 

[sparker]

You do not have a problem.

Scott Parker

 

[chromatica]

If your weight is off by .1 grains out of 55.5 grains, then the error is less than one part in 500. That sounds like an acceptable error for a $100 instrument.

 

[Twoboxer]

Once you've established a load and have its weight from THAT scale, the only thing that matters is that the scale reads the same at that weight every time.

Doesn't matter if the scale says it's 55.4 when it's really 55.5gr . . . that's your load . . . using THAT scale.

 

[mousegunner]

Thanks. I messed around with it and it takes 3-4 kernels of Varget to get it to line up perfectly. FWIW my loads with Varget and IMR 4895 are sub moa for my .223 75/77 bullet loads. Just being too anal and looking for a problem that wasn't there. Thanks again.

 

[cheek9075]

Put the small weight on the scale, let's says it is 10gn. Then put the heavier weight on the scale, let's say its 30gn.

Now put your 55gn bullet on the scale, record the reading (55), now put the 10gn weight on the scale. If the scale goes up 10gn, then the scale is linear. Repeat this with your 77gn bullet and the 10gn weight, if it increase 10 gn then you dont have a problem with the scale. You have a problem with your weights being out if tolerance.

 

[BoydAllen]

If you use that scale to work up a load, and continue with the same scale, there is no problem...none. If you change scales, you might want to compare the weights of the same item on both and note any differences, but for most people a tenth of a grain in a load of that size is indistinguishable down range on a target. Essentially this is one of those you have too much time on your hands things

 

[JohnKielly]

.... one of the reasons that I make a check weight for every load I use regularly.

 

[mousegunner]

.... one of the reasons that I make a check weight for every load I use regularly.

How do you do this?

 

[BenPerfected]

How do you do this?

+1

 

[Depart123]

Alot of guys use a stainless steel screw of some sort ground to the correct weight.

I just got a set of these: https://www.ebay.com/itm/TROEMNER-A...b:g:QzMAAOSwM5tcQ~-z:rk:1:pf:1&frcectupt=true

 

[mousegunner]

Well I do have the RCBS check weights but I may need to double check them on another scale just to be sure

 

[JohnKielly]

How do you do this?

I have a box of various weight oid soft point bullets. Once I've arrived on a load, I trim & drill one of those immediately so it registers the same on the scale, then mark the weight with a scribe.

I have trimmed old keys & coins for the same result, but bullets are easier.

 

[Sheldon N]

How do you do this?

Stainless steel screw or bolt plus a dremmel tool or file.

Keep it clean and it’s a great long term way to make sure your scale and load data is consistent.

 

[47WillysGuy]

How do you do this?

Take a washer and a scale to a drill press and start reducing the weight of the washer to your powder load.

 

[Campbell]

Once you've established a load and have its weight from THAT scale, the only thing that matters is that the scale reads the same at that weight every time.

Doesn't matter if the scale says it's 55.4 when it's really 55.5gr . . . that's your load . . . using THAT scale.

Spot on!

Repeatability is what is required!

 

[Campbell]

I noticed that my 505 is not linear. I keep it clean and covered so it's not exposed to dirt or rough handling.

I've balanced the scale and used my check weights and individually each weight is correct. When I combine them to 55.5 grains it's just a hair off. About the thickness of the line on the scale.

I then used a 55 FMJ and it comes it at 55. A Nosler 77 comes in at 77 grains. I had weighed these some time back and kept them for check weights since they came in right at the numbers.

So, I mostly load .223, .308, 9mm and .45 so I'm not loading heavy powder weights. If the scale is off at heavier weights I don't use does it matter that it's slightly off?

I am going to rebalance it, clean it again and adjust the weights in the pan. Hopefully I can get rid of the slight variance. Anywho thanks for looking.

When you rebalance the scale make sure the beam is perfectly horizontal at the zero point (fairly easy to achieve) AND the line that dissects the angle of the agates is vertical (not so easy to ascertain.)

 

[JimSC]

I calibrate my electronics to 20 grams instead of 100 grams because my normal charge weight with pan is about 15 grams. I figure it is just like a torque wrench and it is most accurate when it is in the middle of it's range.

For a check weight I took a 40 grain bullet and wrote the initial weight in milligrams on a piece of tape and stuck it to the scale. Before each session I check the scale with the bullet and if it weighs within .002 or .003 grams of that initial reading I am good to go

 

[mousegunner]

One more entry then I'm putting this away. Anywho cleaned everything, made sure my base was stable and level. It seemed like it was 3 kernels of Varget on the heavy side when I tried to zero it. I then put 3 kernels into the pan holder, re zero and put the pointer on the line. I put on different weight combinations and took them off and every time the pointer was spot on up to 80 grains, didnt look at anything heavier.

So I'm good, too much time on my hands so maybe I'll redo my corner of the garage with a better bench, start working out again.....thanks for looking and for your responses.

 

[JimSC]

I might be looking at this wrong but for me repeatability is the key feature in a reloading scale. I am not compounding pharmaceuticals I just want 75 loads of powder that are within a reasonable amount of each other, plus or minus .02 grains is plenty accurate enough for my needs. My wind reading and technique are a far cry from a machine rest so 1 kernel of Varget difference will get lost in the "did that mirage just shift and the why did the wind flag at 200 just drop and how will it affect my shot moments". If I can load 75 today that are acceptable, and 75 next week that are the same as the 75 I loaded today I am a happy camper.

I use inexpensive scales and get single digit SD's and isn't that the whole purpose of a load ? Not to see if it is within .00001 grams when tested by the NIST or impress your buddy at the range with how much money you just spent on a new reloading toy. Develop your loads and you should have a .1 gn window on either side of the target weight where being off by plus or minus .1 or will not affect the velocity more than 4 or 5 FPS. For me shooting F class that is plenty. When I were take up 600 and 1000 yard benchrest I will have a $2K Sartoius sitting on my bench but I will address problem when that day comes, if it ever does. At the moment it is nice when developing the load to keep the charges less than .05 grain in difference and that can be done with a $50 Chinese unit from Amazon and mine seems to be within .02 grains of the checkweight bullet every session. I am aware that many use a lot more accurate scales but at the target is there really that much difference if you are loading to a flat velocity node?

just my 2 cents worth