Montana’s attorney general penned a letter, signed by 22 other state attorneys general, urging federal regulators to permanently discard an attempted ban on 5.56 “green tip” ammunition.

The possible ban was introduced in February within a proposal by the Bureau of Alcohol, Tobacco, Firearms and Explosives to change the framework for regulating armor piercing ammo.

Although the ATF put the kibosh on the deal six days before Monday’s deadline for public response, the agency said it will likely revise the proposal after sorting through sum 80,000 comments, which were overwhelmingly critical of the proposed changes.

“We applaud [the ATF’s] recent decision not to issue a final framework on this proposal, at least for now, and we strongly encourage you not to revive it,” reads the letter by Montana’s Attorney General Tim Fox and signed by 22 other attorneys general.

“ATF’s justification for proposing the ban is arbitrary and, if followed to its logical end, could be used to ban a wide range of rifle ammunition. As we are sure you are aware, just about any rifle round could theoretically pierce soft body armor under certain conditions,” the letter argues. “The M855 is not unique in this regard. And although concealable handguns can technically be chambered in these rounds (even if very rarely), that is an insufficient reason to ban ammunition absent actual evidence that it poses a particular threat to law enforcement.”

Rounds made of M855 cartridges and SS109 bullets — identified by its green tip — is standard military issue ammo. While not an explicit ban on the ammo, the ATF said under its current process for regulating armor piercing rounds, it would be prohibited since pistols are available that can fire it.

Green tip ammo has been exempted for sporting purposes since 1986, when the law that defines armor piercing ammo passed for the protection of law enforcement officers.

“The 5.56 M855 cartridge does not pose a particular threat to law enforcement … we are aware of no examples in our states in which this round has been used against law enforcement in a concealed weapon,” the letter reads.

“ATF’s decision to ban it would, simply put, be an abuse of its authority,” it continues and concludes, “We strongly encourage [the ATF] to reject this ill-advised proposal and uphold the Second Amendment rights of our citizens.”

Attorneys general from Alabama, Arizona, Arkansas, Florida, Georgia, Idaho, Kansas, Kentucky, Louisiana, Michigan, Mississippi, Nebraska, Nevada, North Dakota, Ohio, Oklahoma, Pennsylvania, South Carolina, South Dakota, Texas, Utah, and Wyoming joined Montana in the letter.