The Auto-Ordnance Thompson M1 SBR .45 ACP is the short-barreled version of the Thompson M1 pattern of World War II, built with a 10.5-inch smooth barrel (Auto-Ordnance part no. M1SB). Like the original M1, it drops the finned barrel and vertical grip of the 1927 pattern in favor of a plain barrel, a fixed battle rear sight and a horizontal walnut foregrip. The frame and receiver are machined from solid steel with a blued finish, and the action is semi-automatic from a closed bolt. It measures 32 inches overall and weighs 10.5 pounds, so it is lighter and shorter than the 1927A1 SBR. It suits collectors and range shooters who want the wartime M1 profile in a compact package.

Key Specifications

• The chambering is .45 ACP, the round the Thompson was built around.
• Barrel length is 10.5 inches with a smooth profile, true to the simplified M1 pattern.
• Overall length is 32 inches, the most compact of the Thompson SBRs.
• Weight is 10.5 pounds, enough mass to keep .45 ACP recoil soft.
• The action is semi-automatic, firing from a closed bolt, which keeps the trigger consistent from shot to shot.
• The frame and receiver are machined from solid steel, a durable build for a gun meant to be shot.
• The stock is fixed American walnut, matching the look of the wartime rifles.
• The foregrip is a horizontal walnut forend, the M1 layout instead of the 1927 vertical grip.
• Sights are a blade front and fixed battle rear, a simple, rugged setup with nothing to knock out of adjustment.
• It ships with one 30-round stick magazine, a full load for a range session.

Frequently Asked Questions

How is the M1 SBR different from the 1927A1 SBR? The M1 SBR has a smooth 10.5-inch barrel, a horizontal foregrip and a fixed battle rear sight, and it is 32 inches long at 10.5 pounds. The 1927A1 SBR has a finned barrel with a compensator, a vertical foregrip and an adjustable rear sight, at 35 inches and 12 pounds.

Do I need ATF approval to buy this? No. As of October 9, 2026, ATF no longer requires Form 4 approval, registration or a tax stamp for short-barreled rifles. It transfers on a Form 4473 with a background check through a Class 3 (SOT) dealer. State and local laws still apply. Taking an SBR across state lines still requires an approved ATF Form 5320.20.

What finish does it have? The steel frame, receiver and barrel are blued, paired with American walnut furniture.

Buy the Auto-Ordnance Thompson M1 SBR .45 ACP, 10.5-Inch, Walnut Horizontal Foregrip

As of October 9, 2026, this short-barreled rifle transfers on a Form 4473 with a background check at your Class 3 (SOT) dealer, with no Form 4 or tax stamp; state and local laws still apply. Order through Auto-Ordnance‘s short-barreled rifle lineup and our Lubbock, Texas team will handle the transfer.