...I'Ding iron with the X5 is relatively easy, but you HAVE to spend the time in the field with it to hone your skills. I ID iron in essentially three different ways.
First, iron is almost always a harsher and rougher sound. NOT mellow and smooth like a desireable non ferrous target.
When I get a signal I suspect is iron, the FIRST thing I do is is check it out in VCO . Push the pinpoint button, and "size " the target. Iron often has a huge footprint, and the VCO signal will "ramp up" differently on iron than it will on a good target. If you push the VCO and slowly swing over an average non ferrous target, the sound will come up slowly and smoothly. Do the same on iron, and will will ramp up really quick. Shallow iron will literally scream at you.
I use the coin check to ID iron as well. Its one of the better tools for doing this.
When you are checking a target, listen to the response in both coin check positons, as well and the normal one. What you are looking for is a clean break in the response. that is, when you push the Coin check in either the up or down positions, your looking for the beep to either go away completely, or stay completely.
If it "breaks up" or gets chattery, its usually iron.
I've got to clarify that a little bit. Sometimes you will get a lower conductive target that will give you an iffy signal in the lower position, but it will be gone completely in the upper position. I usually dig these.
They are often a target thats right on the break point of the discriminator. If it breaks up in BOTH positions however, it almost always iron, especially if its the upper one .
Also, I usually circle my target if I'm really not sure. Good targets will tend to (but not always) stay the same if you attack them from different directions, but iron will change on virtually every sweep.
When you do your sweeps, be sure you directly on the target too. Iron will often give you a decent sound of you just sweeping the edge of it.
Re-center, and swing directly over the center, and your response will change. Now, there are exceptions to every rule, and only with experience will you be able to make judgement calls in the field on whether or not to dig. When it doubt, DIG IT!! All this may seen like a lot, but in practice, it takes only SECONDS to do an evaluation in the field. With practice, you'll get better and better at it.
At the moment my X5's are the only machine I use, I have tried others but they just don't cut it for me.
I was tempted to have a whirl with a GoldMaxPower, but then Troy rang for a chat...so I wait.
One thing I didn't mention about VCO whilst on the topic, is that if you very quickly push it a second time, you will find that it narrows the target centre very significantly, again emphasizing the larger footprint iron gives.
Hope this helps,
Dino