The Bureau of Alcohol, Tobacco, Firearms and Explosives quietly published a new guidance document Tuesday morning titled Clarification of Terms Related to Firearms, Firearm Accessories, Firearm Components, Firearm-Adjacent Items, and Other Items Which May or May Not Be Firearms Depending on Circumstances and Configurations, and before you ask, yes, that's the actual title.All 472 pages of it.The document, which TFB obtained through the ATF's public resources page, sets out to definitively answer the question that has haunted gun owners, manufacturers, and apparently the agency itself for decades: what, exactly, is a firearm? Here's What They Landed OnAfter three years of internal review, six rounds of public comment, and what the document describes as "extensive consultation with relevant stakeholders," the ATF has concluded that a firearm is:"A device, assembly, component, or related object which, under defined and applicable conditions, may or may not constitute a firearm as defined under 18 U.S.C. § 921, subject to revision."So, there you go.Page 12 does clarify that a pistol is not a rifle unless it has a stock, at which point it may be a rifle, or a short-barreled rifle, or neither, depending on brace configuration, intent, and whether the end user has filed the appropriate paperwork, which may or may not be the right paperwork.Pages 13 through 31 are entirely devoted to the question of whether a solvent trap kit is a firearm suppressor. The conclusion, on page 31, is: "It depends."Some Other HighlightsPage 7 contains a flowchart for determining whether an unfinished lower receiver is a firearm. The flowchart has 23 decision nodes. Eleven of them loop back to node one. There is a footnote on page 7 noting that the flowchart "should not be used for legal compliance purposes." Page 39 introduces the concept of a "firearm-adjacent device," which the document declines to define, but notes that such devices "may be subject to future rulemaking."The document also helpfully clarifies that forced reset triggers are not machine guns, except when they are.What This Means for Gun OwnersHonestly? About the same as before.The practical upshot of 472 pages of federal guidance is that you should probably call your attorney before buying anything interesting, avoid any accessory whose product description includes the word "solvent," and under no circumstances mail anything to anyone in New Jersey.The document does not address pistol braces, binary triggers, 80% lowers, oil filter adapters, auto sears, or bump stocks, noting in Appendix C that those topics will be covered in a forthcoming "supplemental clarification document" expected sometime in Q3. Of an unspecified year.The ATF did not respond to a request for comment. They did, however, send an automated reply confirming receipt of TFB's inquiry and noting that response times may be delayed due to "high volume."Happy April 1st from TFB. The ATF document above is fictional, but we're not entirely sure the actual regulatory situation is that much clearer. Stay safe out there, and as always: Firearms Not Politics.