CMMG PS90 10.4" SBR Barrel

The CMMG PS90 10.4-inch barrel is the standard path to a short-barrel PS90. CMMG cuts the barrel from 4140 chrome-moly steel, finishes it in salt bath nitride, and threads the muzzle M12x1.0 left-hand so it accepts CMMG's PS90 muzzle hardware. A compatible muzzle device is required for correct barrel retention; the barrel will not install or run reliably without one.

Because the M12x1.0 LH thread is non-standard for the US suppressor market, mounting a typical 1/2x28 5.7x28 can requires the CMMG M12x1.0 LH to 1/2x28 thread adapter. Fitting the 10.4-inch barrel makes the PS90 a short-barreled rifle. Federally the making tax is $0 and, since October 9, 2026, ATF does not enforce Form 1 approval or registration for SBRs, but some states still tie SBR possession to federal registration, so check state law first, and file a Form 20 before taking it across state lines.

The 1:9 twist is appropriate for SS197SR and SS198LF 5.7x28 loadings. Cutting the PS90 to 10.4 inches restores the original P90 balance and shortens the package by roughly five and a half inches versus the factory 16-inch barrel.