We've covered the Silencer Shop Foundation v. ATF ruling when it came down and again when the stay expired. Two updates are worth flagging now: the government's ordinary appeal window on that ruling remains a separate question from the expired emergency stay, and Missouri has filed its own lawsuit advancing a similar argument.
The appeal deadline that's still sitting out there
When we last checked in, DOJ hadn't asked for a stay or filed an appeal by the time the original seven-day pause expired — which we reported accurately at the time. The ordinary deadline for a federal party to appeal is a separate procedural question, however. Reporting has identified October 5, 2026, as the expected deadline. No appeal had been publicly reported as of publication, but "hasn't appealed" and "can't appeal anymore" are different things. If that deadline passes without a filing, it will be a stronger signal about the finality of this particular district-court judgment.
A second state has now filed its own, separate suit
On September 8, 2026, Missouri Attorney General Catherine Hanaway, joined by Missouri resident Dave Marshak, sued ATF and DOJ in the U.S. District Court for the Eastern District of Missouri. It is a different court and circuit—the Eighth rather than the Fifth—from the original case.
The legal theory tracks the original ruling closely: suppressors, short-barreled rifles, short-barreled shotguns, and "any other weapons" all had their federal making and transfer tax reduced to $0 as of January 1, 2026 under the One Big Beautiful Bill Act, and once that tax hits zero, Missouri argues, the registration, fingerprinting, and approval requirements built to collect it lose their constitutional footing entirely — the same Sonzinsky v. United States tax-power reasoning underlying Judge Hendrix's August 5 ruling in the original case.
Missouri's complaint adds a Second Amendment claim, backed by ATF registration figures that the complaint puts at roughly 6.65 million suppressors and 1.23 million short-barreled rifles nationally. Missouri argues those numbers weigh against treating the items as "dangerous and unusual" weapons outside Second Amendment protection. The complaint then argues that the government cannot identify a sufficiently comparable historical tradition for a modern national registry backed by fingerprints and criminal penalties. Those are the plaintiffs' arguments; the court has not adopted them.
Why this matters even though it's not a Colorado case
The Missouri case does not change the rules in Colorado. A district-court ruling there would not bind Colorado courts. What it does show is that the zero-tax theory is now being tested in more than one court by different plaintiffs. For Colorado residents, the open question we flagged in our original coverage hasn't changed: C.R.S. 18-12-102's affirmative defense for suppressors and short-barreled rifles still points to federal paperwork that may or may not keep being issued, and the Missouri filing does not resolve that state-level question.
Bottom line
Nothing has changed on the ground for Colorado owners since our last update. What's changed is the scope of the dispute: similar but not identical arguments are now being made in separate federal courts, while the possibility of an appeal in the original case remains worth watching.
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