Help with a 505 scale?

[earthquake]

I just started reloading and have a hand me down RCBS 505 scale. It seems like a nice unit and always returns to zero when I remove weight, but recently I noticed that maybe it's not calibrated correctly or...?

This past week I got around to charging my first loads so I wanted to make sure it was reading correctly. I placed several Berger 130 and 140 grain bullets in the scale from a "zero" starting point and they ended up not reading the correct weight. I find it hard to believe that all the bullets I measured are wrong.

I then adjusted the levelling foot on the scale to the "zero line/mark" with a bullet in the pan, but when the bullet is removed, the scale does not got back to the "zero" line/mark.

"Zeroed" out with a 140 gr bullet...every bullet returns to this exact same point from a starting point pictured below....
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Point returned to once bullets removed....
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I've messed with adding/removing weight/shot to the pan holder below and it doesn't seem to help. Could it be my bench is not perfectly level? Any advice/tips/help appreciated!

 

[Nate O.]

If you haven't already, make sure the fulcrum is clean or otherwise undamaged.

Sent from my XT1080 using Tapatalk

 

[mtrmn]

Most bullets will not quite weigh out exactly to the labeled weight. As long as the scale returns to the same zero every time it's OK.

Just zero the scale with an empty pan and be sure you don't move the scale during use. If your "140 gr" bullets wind up weighing 140.2 gr or 139.8 gr it's no big deal. Mostly as long as they're fairly consistent you'll be OK. One tenth of a grain is one seventy-thousandth of one pound. Match bullets vary maybe 2 or 3 tenths of a grain from one another IME. FMJ's can vary as much as 2 grains from the next one.

The weights in the silver pan holder are for making sure the BEAM is LEVEL when the scale is zeroed. The scale will react to weight in the same manner no matter what these weights are adjusted to as long as the scale can be zeroed.
You need to zero the scale and compare the beam to a spirit (bubble) level. Add or remove weights until until the beam is level at zero. Then leave it alone.

If you want to check the accuracy of your scale you need a set of check weights. You cannot depend on a bullet weighing exactly what the box says it does. The weights are for sale all over ebay and other sites. Make absolutely sure everything on the beam and the pan etc is perfectly clean. This scale is capable of weighing dust. Don't let that throw you off.

OR maybe I completely misunderstood the question---the more I look at it the more doubts I have.

 

[earthquake]

The weights in the silver pan holder are for making sure the BEAM is LEVEL when the scale is zeroed. The scale will react to weight in the same manner no matter what these weights are adjusted to as long as the scale can be zeroed.

You need to zero the scale and compare the beam to a spirit (bubble) level. Add or remove weights until until the beam is level at zero. Then leave it alone.

Thanks for the help! I'm not quite sure about how to compare the beam to a spirit bubble level, which I do have access to. Is there a spot on the scale to set one (I haven't found an ideal place), or do I place it on the same table and "eyeball" them?

 

[delixe]

I think of it this way.
I have a pretty nice digital balance (A&D FX-300i).
I have a cheap calibration weight.
Even if the calibration weight is off, as long as I calibrate with the same weight when I use the balance, my charges will always be correct relative to each other.
Now, if I were to share my recipes with someone else, their scale may not exactly match mine, but we don't really do that anyway, do we?

As others have said, level and zero it every time you set it up. It'll be fine.

 

[mtrmn]

Thanks for the help! I'm not quite sure about how to compare the beam to a spirit bubble level, which I do have access to. Is there a spot on the scale to set one (I haven't found an ideal place), or do I place it on the same table and "eyeball" them?

I set my scale up on the bench and place a suitably-sized box or something behind the scale so I can see my torpedo level behind the scale beam. Make sure there are no air currents like a ceiling fan or AC vents blowing-this will affect the scale. Remember this when you use it as well.

Make sure the level is level by shimming under the low end until your bubble is right, then eyeball the scale beam in relation to the level by comparing the straight edges. This may not get you perfect, but extremely close. Remember-you're leveling the BEAM at zero setting--make sure the pan and everything else is empty and clean. Make sure the little sliding weights are in their grooves-if one is just a little out of place it will affect your readings. All set to zero.

It doesn't even matter if you have the base of the scale set to zero in relation to the beam pointer-all you're doing is determining how much weight to add/subtract to level up the BEAM in relation to your level. See which way you need to go and disassemble the pan holder to add/subtract weight. If you don't have the little lead shot you can use anything durable--pea gravel or something. IT DOES NOT TAKE MUCH TO HAVE A BIG EFFECT.

Delixe has it right as well. When you work up your perfect load with your scale, it will always be right with your scale. Change scales and that one may be off from your other one a tiny amount. Note the difference and carry on. Always verify a digital scale with a check weight or a beam scale. I've seen a lot of electronics (not just scales) go completely nuts or just tell little lies and I will never be able to completely trust them.

 

[seanhagerty]

Delixe has it going on there. It does not matter if you are exactly the weight you are reading, as long as you are consistent. If it reads 142gr, but you really have 141.8gr, you are fine as long as you always read 142gr when its 141,8gr.

I dont buy check weights. I weigh a washer two or three times on different days, then put it in a plastic baggie marked with what I read as its weight. Wa-La! Home made Check weight! As long as my scale always reads that weight, I am good to go. If it reads something else, then I need to investigate.

 

[Bob munden]

Turn off the fan in the room, or the heat vent blowing near your reloading area, my scale is all over the place with the slightest breeze!

 

[bigedp51]

These scales have magnetic damping, if anything is producing static electricity near the scales it interferes with the magnetic field and can throw the weight off.

Bottom line no plastic underneath or around the scale and this also means the "plastic" powder cans.

http://www.rcbs.com/downloads/instructions/Model505ScaleInstructions.pdf

 

[plh]

Much of what follows has been said. Consistency in readings on Thurs. and Sun., in March and Sept. is what's desired. I found a pet charge on the 505 scale and ground down a penny to match that weight exactly. As i weighed out charges I could intermittently check my zero without movement of the poise settings. Additionally, the larger poises will sit in the indents slightly forward or rearward and can change ever so slightly as the beam bottoms out thereby changing the zero reading, so care must be taken to gently place/remove the pan. If the beam bottoms/tops out aggressively, time to recheck the zero and recapture by tickling or tapping the larger poise with a toothpick. A USB camera was essential for me to confirm all these things. Is this all borderline insane? Yea, and all these permutations accumulated over many months of weighing charges. I'm now fortunately weighing with a Sart. GD503 and the 505 is in the box. I will say that I was able to demonstrate over eleven 43.0 gr. charges using this protocol on a Scott Parker tuned Redding #2 a spread of .055 gr. and a sd of .016 gr. of Varget as checked on the Sartorius. Excellent accuracy is there to be had on a rudimentary balance beam scale, but it requires rapt attention to detail......IMHO.