Tennessee House Bill 1924, proposed by Rep. Henry Fincher:

(a) This section shall be known and may be cited as the “Second Amendment Protection Act”

(b) As used in this section, “microstamped” means the technology by which a laser or other device is used to make precise, microscopic engravings on the internal mechanisms of a firearm for the purpose of ballistic imprinting, such as the firing pin, breech face or other internal mechanism, or the casing of a cartridge, so that when the firearm is fired, information identifying the make, model and serial number of the firearm, or the purchaser of the ammunition, is stamped on the discharged cartridge case and can then be matched to a specific firearm, purchaser or purchaser of ammunition.

(c) It is a [misdeamanor] offense for a person licensed as a firearm dealer under 18 U.S.C. § 923, to transfer, sell, deliver, or offer for sale, delivery or transfer, in this state any new firearm, as defined in § 39-11-106, or any firearm ammunition knowing that the firearm or ammunition has been microstamped.

(d) The owner of a firearm or firearm ammunition lawfully acquired may have such firearm or ammunition microstamped provided it was not originally sold in a microstamped condition in this state.

So a gun dealer chooses to sell a microstamped gun, and a gun buyer is perfectly willing to buy it, and that's a crime? I don't think that microstamping mandates are likely to do much good, but I see little justification for banning the sale of microstamped guns or ammunition (as opposed to not mandating such sale).

I should note that I don't think that either microstamping bans or microstamping mandates violate the right to keep and bear arms for self-defense. (I haven't thought enough about the right to keep and bear arms for other purposes to opine confidently on that, though I suspect that they don't violate such a right, either.) But I don't see a law controlling microstamped guns as sensible or just.