If the targets you are seeking provide the same inductive and conductive information to the detector as certain pulltabs, they will provide the same TID number. Here is an excerpt from an article written by Bruce Candy of Minelab, explaining the science behind discrimination.
Metal detectors differentiate between different non-ferrous targets by measuring how well eddy currents flow in them. This is determined by a target’s “time constant. Two properties of a metal target determine its time constant. One property is called the target inductance. This inductance may be thought of as the effective “mass” of the eddy currents, and which is basically the size of the eddy current path. Thus, for a given eddy current flow, the bigger the effective target inductance, the bigger the “momentum” of the eddy currents. Another property is called target “conductivity,” which is a measure of how easy it is for eddy currents to flow. This is the opposite of electrical resistance. High conductivity (low resistance) means the eddy currents flow easily (low current “friction”). Low conductivity (high resistance) means high eddy current “friction.” The better the target conducts electricity, and the bigger the inductance, the longer the time constant. Most coin detectors may be set to select various ranges of non-ferrous time constants. For example, the old pull tabs of soft drink and beer metal cans have moderately short time constants in a fairly narrow range. This time constant range may be discriminated against, but targets with differing time constants will still be detected. This range may be selected by a “notch” discriminator control. However, other targets with time constants very similar to the pull-tab time constant range will also not be detected, so some care should be taken in setting the discriminator controls.
If you would like to read the entire article,Metal detector - Basics and Theory - by Bruce Candy, it can be found in the Knowledge base on Minelab's website. http://www.minelab.com/__files/f/11043/METAL%20DETECTOR%20BASICS%20AND%20THEORY.pdf
The best way I've been able to discern variances in the audio response of most pull tabs is to vary the sweep speed of the coil (after initially hearing the target response). If I flip the coil back and forth over the target very quickly, the audio response of pulltabs will sometimes break up. The problem is......you'll need to dig the first 500 of them, to prove it to yourself that you are actually hearing a difference in sound (compared to a coin). Then, after that first 500, you'll still dig them occasionally, just to reinforce your diagnosis! And don't expect all good targets to sound smooth and solid...Depending on the coil, depth and angle they are buried, coins on edge can also provide a broken audio. I've also dug quite a few rings that didn't lock on solid audio. Many of them have had broken bands. Much of what I listen for will depend on what I am hunting for, and the types of targets I might come across. As I get older and the body doesn't work as well as it did at one time, I prefer to hunt for old coins at old sites...just to not have to deal with modern trash. JMHO HH Randy