What am I doing wrong with my 505?


July 25, 2007, 10:26 PM
I just bought a brand new RCBS 505 scale.

It wont zero.

To see how far off it is, I weighed four 125 grain bullets.
The average weight I got was 117.5.

Did I set the scale up wrong or did I buy a broken one?

What do you think????????

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July 25, 2007, 10:59 PM
Have you zeroed the scale? You said it won't zero, but I'm not sure what you mean. Do you not know how? I'm not being condascending (especially since I can't spell that word.)

Assuming that you did follow the instructions...

bullets are a poor substitute for a set of check weights. Get a real set and then you will know for sure if your scale is off.

July 26, 2007, 01:26 AM
On balance beam scales it's important to keep the pivot points clean of dust and debris, and to make sure the pivot points are seated properly in the cradles. The scale also needs to be as level as possible, and then the adjusting screw moved until the pointer on the beam is centered on the proper mark. Check those things and then start over with weighing and see if it makes a difference.

Also, if you're weighing cast bullets, they will vary more in weight than jacketed bullets from a reputable manufacturer.

Hope this helps.


July 26, 2007, 05:37 AM
I think the bit that makes me wonder the most is the comment:

"it won't zero"

If that's the case then that's the first problem you have to solve. I can't remember if the 505 is one of the one's where you can adjust the thing that hangs off of the arm and holds the powder pan or not? If it is then the instructions should tell you how to do it . typically it's with lead shotgun shot if I remember correctly.

I'd get the thing zero'd correctly first then see how they weigh out. My experience has been that for cast boolits the weight on the box is a guideline typically following the mold used to drop them . . . (but they should be relatively consistent if the caster is any good) quality jacketed bullets from someone like Sierra should be be pretty much dead on weight wise to what the box says.

Just my .02


July 26, 2007, 09:46 AM
You turn the plastic leg in and out to zero the scale....
Make certain you're on a level surface to start with too!

The Bushmaster
July 26, 2007, 01:52 PM
Thanks mrkubota...You saved me from having to say that it must be on a level surface and you adjust it with that little wheel at the base to your left if you are right handed (the pivot end). I also agree that bullets are a piss poor calibration weight.

July 26, 2007, 04:22 PM
The scale is on a flat surface.

All the weights are in the zero grooves.

Pan in place & beam is pegged out at the bottom.

I'm loading for cowboy action using Trail Boss powder; my Dillon press was set up to drop 3.2 grains.

I had to dump almost all the powder from 2 casings to get the beam to move.

July 26, 2007, 04:33 PM
Make sure the beam is set in there straight, and not rubbing or contacting anyplace except the pivot points.

When you zero the scale, the pointer should be at the long line in the middle of the measureing scale, so it can freely move up and down, with everything set in the zero positions.

The beam shouldn't be "pegged at the bottom". It should be right in the middle and even breathing on it heavily should move it.

Hope this helps.


July 26, 2007, 04:55 PM
You're using the brass pan aren't you?:)

July 26, 2007, 04:57 PM
You have the little aluminum pan don't you?
The only thing I can think of is that you have the wrong pan and it's too light. A balance beam scale doesn't have much to go wrong with it, if the knife edges are in the right spot and are moving freely.

Steve in PA
July 26, 2007, 04:59 PM
Um, the beam is not supposed to be pegged at the bottom. The beam, with the pan and all weights set to "0" is supposed to center in the middle. Adjust the leveling device to adjust the center.

July 26, 2007, 05:16 PM
Call RCBS, If they cannot help you to "zero" it they will make it good and replace.

July 26, 2007, 06:15 PM
Steve in PA is right with the weights set to there zero position and the empty powder pan in place you need to adjust the leveling screw on the bottom left side of the scale. Adjusting this up or down will cause the pointer to move up or down, you want the pointer to be in the center of the scale.


July 26, 2007, 06:48 PM
The scale is fixed.

The pan that the brass scoop sits on has a hollow base.
The base opens up and has shot and what looks like really little tiny bits of weld splatter.

Just had to adjust the amount of shot & splatter (4 or 5 times) till the beam was on zero.

I learn something new every day, well every year anyways.

Steve in PA
July 26, 2007, 10:55 PM
Well, I guess thats one way to zero it, but not the correct way.

Steve in PA
July 26, 2007, 11:04 PM
You do know that the round white object on the bottom left is what you turn up or down to level the scale.


July 26, 2007, 11:04 PM

I turned the leveling foot all the way in & all the way out.
Beam stayed just like the picture, except that all three poise were in the zero grooves.

Tilted the scale to 45 degrees both up & down.

I took it back to the gun shop and they fixed the pan weight.

July 27, 2007, 01:32 AM
I have the exact same problem with a used 5-0-5 I bought. Nothing I do will zero the scale (regardless of the front adjusting foot) short of picking the front up at a ridiculous angle. I guess I'll try the method the OP found.

Steve in PA
July 27, 2007, 01:47 AM
If it was stuck like in the picture, then the part that holds the pan had no or very little weight in it?

July 27, 2007, 12:07 PM
Right, the pan acts as the counter weight for all that beam sticking out the other side.

I think maybe my pan got switched at the packing process.

At the gun shop when we were problem solving, he pulled the pan from an other scale and the beam went all the way up because that pan was heavier

July 27, 2007, 04:55 PM
To be sure it is set up correctly you need to get a set of check weights and test it with different known weights. Your new zero may still not be a true zero point. Checking with known weights will tell you how far off it is. Start with a low weight and keep increasing the weight over the full span to see if it holds zero.

Lets say you started with the scale set at Zero and then added a 10 grain test weight to the pan adjusting the scale to 10 grains should cause the pointer to move to zero (center of scale), If you go through these same steps with a 100 grain test weight and it will not zero when you set the scale for 100 then it is still not set up correctly.


Steve in PA
July 27, 2007, 07:30 PM
Okay then that explains the confusion we were having. Looks like RCBS had a little quality control issue there.

July 28, 2007, 10:17 AM
Best bet already mentioned is call RCBS. They will help you straighten it out whatever it takes. Now I'm going off memory from seven years but
I seem to recall a screw in the pan support that when taken off opens a reservoir for shot to put in the correct amount of counterweight and I believe mine came with a small bag of shot for that purpose.

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