An etching reagent is used to recover serial numbers.

Restoring a serial number can provide law enforcement agencies with information about a firearm or other item and may offer a lead in an investigation. Generally, scientists will polish the metal with a sand-paper type material to remove chips of metal from the surface.

Serial numbers were removed by grinding to a point just beyond obliteration. The handbook reports on the results of optimizing several restoration methods: chemical and electrolytic, ultrasonic cavitation etching, magnetic particle, and heat treatment.

The new method uses magneto-optical (MO) sensor technology to nondestructively detect and visualize serial numbers that have been scratched, ground, chiseled or otherwise removed from firearms.

Chemical etching is the most common and successful method for restoration of serial numbers on the metal surface.

While most firearms do not have hidden serial numbers, there are several exceptions.

The only way to a make a bullet untraceable to a gun that can still be used again is to totally change the barrel, and use caseless ammo. Not only the bullet, but also the case of the round of the evidence is in the database.

You can conceal carry a ghost gun in all states except California, Connecticut, Hawaii, New Jersey, Rhode Island, Washington, and the District of Columbia. Federal law does not prohibit self-assembled firearms but does ban firearms that are undetectable by a metal detector or x-ray.

You still need a weapon to compare it to for positive identification. A jacketed . 22 caliber bullet can be identified by the lands and grooves left on it by the rifling of a weapons barrel the same as any other jacketed bullet can to a point.

As the bullet passes through a suppressor, the gasses are trapped in order to suppress the sound and muzzle flash. This process has no effect on the original striations left on the bullet once it exits the barrel.

Unless improperly installed or attached, suppressors do make shooting more accurate. Less muzzle rise, less sound and less concussive effect also help a shooter improve accuracy. As long as they do not come loose and are installed properly, modern suppressors will do nothing less than enhance a shooter’s accuracy.

Depending on the type, yes. In addition to signature deviations in land and groove markings, some suppressors have an outlet port rubber starfish which can leave some residue. Also some suppressors affect accuracy.

A suppressor will shift the point of impact consistently with each mounting. This shift will be different for each firearm it’s mounted on. Suppressors generally improve a firearm’s accuracy.

Silencers also add length and weight to your firearm, changing the balance you’ve practiced with and possibly affecting your accuracy. Some silencers will change the barrel harmonics and shift your expected point of impact. Those are all the disadvantages of silencers I can think of not related to legalities.