RCBS 505 Not Calibrated

A

ADClope

New member
Hi all,

I am new to reloading, and recently picked up an RCBS 505 scale and a set of Lyman check weights. Tonight I checked the scale against all of the check weights and the scale was consistently off by about 1.1 to 1.2 grains. To me this seems substantial.

Is there a way to calibrate this scale or how do I correct this?

I mean, I suppose I can just account for the inaccuracy, but I'd much rather not.

Thanks! :)
 
If you haven't, place all 3 poises to ZERO. Then screw the leveling foot up or down until the pointer is exactly on zero. Then use your check weights. Don't want an inaccurate scale. 1.1 to 1.2 grains can mean a safe load or a dangerous one.
 
Correct, if your scale will not zero with adjusting the foot up or down then the "ballast" in the weigh pan is not the right weight. There is shot in the bottom of the pan. You can loosen the cover holding the balance weight shot and add or even remove one piece of shot and retest. If that doesn't work RCBS has good customer service.
 
ADClope

If the scale is NOT new ie, used or unknown to you,

Carefully remove the beam,
check the agate pivot "V" bottom, one on each side, the beam pivots ride in/on, to make sure they are not cracked, chipped or broken etc.

Take a "Q" tip with alcohol and thoroughly clean these pivot points, dust build up here up can effect the readings.

Check the knife edges of the beam arms to make sure they are NOT rounded off/over, bent etc.

Carefully replace the beam, set all 3 poises to ZERO, level the scale to the zero mark,
carefully slide the beam pivot arms to the extreme right and left of the movement area,(between the side plates),
if the beam pivot arms drag or hangs up on these plates, it can effect the readings,
you want the beam pivot arms to be centered and free to move freely,
check the zero reading.

Set the beam pivot to the center area of the agate slots/"V" area,
there is a very small spacing/distance of play between the plate holders of the base,
use the check weights and check the readings -vs- weights,
the center poise weight (whole gr) is notorious for NOT being completely down in the slot selected, which can and will give false readings etc.

HTH,

Tia,
Don
 
As far as calibrate, the only way is to start with the scale at zero, add a check weight and read the weight the scale gives you. Run through all check weights and combinations and graph them--say, check weight on x-axis and scale weight on y-axis. This graph is your calibration.
But, of course, that really is not your concern--you want to get that scale checked and fixed.
 
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