Is microstamping the answer?

A recent hype in gun crime reduction is microstamping, it boils down to this:
When a criminal shoots somebody with a self loading weapon, he often leaves behind cartridge casings. Microstamping the components of a gun which come into contact with the casing would allow for symbols to be placed on those casings as they are fired. which can the be traced back to the gun, and to the original owner of the gun.

The Brady campaign has placed links to a series of videos hosted on youtube concerning microstamping, those videos can be found here:
http://www.youtube.com/watch?v=L_bH1g5xRT4
there are a total of six parts to that movie

The components would be engraved using a pulse laser. I personally have most faith in engraving the firing pin and the breech face. The latter is the only one which cannot be easily replaced, though still occluded or defaced. The extractor and ejector are simple solid pieces of metal which can easily be replaced by self-made replacements. It's plausible that criminals will go through the trouble of doing this. The firing pin too can be defaced or replaced by a home made variant, though it's not as easy to manufacture one yourself. Also, defacing a firing pin may result in a less reliable firearm. (depends on make and model)
The ease with which the breech face of a handgun can be defaced depends entirely on the type of the firearm. It can be remarkably easy or hard.

When would it be applicable?

Not all guns eject spent cartridge casings, according to "guns used in crime", a publication by the bureau of justice statistics / us department of justice, 51.5% of all stolen handguns are revolvers, those do not automatically eject cartridge casings after each shot.
However: the 10 most traced models of firearms all ejected casings (shells in one case, the mossburg 500 shotgun, though this one doesn't do so directly after each shot. (12ga). (1994)
The same study also provides good documentation concerning homicides in Philadelphia (1995), 95% of all homicides were committed using handguns, 66% of those were revolvers, 23% of the time, a semi-automatic handgun was used.

Note: the 11% which is unaccounted for is not explained, however it's often impossible to determine within acceptable certainty whether a shot was fired from an autoloading pistol or a revolver, because certain cartridges can be fired from either.

Microstamped casings will only be recovered in a limited amount of cases. A lot of times (sometimes the bigger part), the weapons used do not eject casings after each shot. Furthermore, autoloading pistols can be fitted with "brass catchers", simple contraptions which capture the ejected cartridge casing. These are commonly used by target shooters who load their own cartridges.

This brings us to another point of criticism: cartridge casing can be re-used easely. People commonly collect casings from shooting ranges to sell online Only newly manufactured guns could be fitted with microstamped components. It would take a while for the current supply of illegal guns to dry up, but it would happen over time, a very log time. Not only is this one more thing to take into consideration as we compare cost to effectiveness, but it also means that as long as there are still non-microstamped guns in circulation, the casing may lead to the wrong person.
If somebody were to buy a microstamped gun and take it to the range and shoot it, but chooses not to collect his casings, or tries to but misses one, this would effectively mean that there's a stamped cartridge out there ready to be reloaded and re-fired.
Anybody with such casings, some basic tools and the information provided on the internet could manufacture cartridges which would incriminate a completely innocent person!

There was an elaborate article in the AFTE journal vol.38-1 2006, reviewing microstamping. The main point there was that if somebody used a microstamped gun in a crime, several cartridges may be necessary to be able to read the information stamped on the casing, because a lot of the information from the components is not transferred to the casing.
Some types of firearms are will transfer this information considerably better however, as seen in the video's sponsored by the Brady campaign.

So what happens after: "Shots are fired, casings have been ejected (less than 50% of the time), Casings are recovered and the serial number of the firearm is found."?
Using this information, the original owner of the gun is paid a visit and inquired about the current whereabouts of said weapon. Maybe there will be some cases where the weapon hasn't been reported stolen. Fat chance? I'm afraid not.

I'm not adversed to microstamping, I think it's a valid technique to be used in forensic science. My condensed opinions.

-It can only work in a severely limited amount of cases.
-Trying to keep track of people who let their guns get stolen once a month seems less work
-There has not yet been a full evaluation of the implementation price, I want to see one.
-It's very easy to get around the technology, especially if the crime is premeditated.
-If not premeditated, one only needs the calmness to pick up the casings.
(unless a revolver was used

I'm not buying into this, yet ... if it turns out to be extremely cheap, then sure, why not? (Note: I'm well aware that the price might turn out to be astronomical) But I'm not getting my hopes up, and the Brady campaign shouldn't be getting peoples hopes up either.