The Auto-Ordnance Thompson SBR .45 ACP detachable buttstock model pairs a 10.5-inch finned barrel with a walnut stock that comes off the receiver (Auto-Ordnance part no. ZT1BSB). With the buttstock fitted it measures 35 inches, and with it removed the gun shortens to 25.5 inches for transport and storage. The action is semi-automatic from a closed bolt, and the frame and receiver are machined from solid steel with a blued finish. A walnut vertical foregrip completes the 1927-style profile. It is the Thompson for owners who want the classic look and the option of a much shorter package when the stock is off.

Key Specifications

• The chambering is .45 ACP, the Thompson’s original cartridge.
• Barrel length is 10.5 inches, finned, and 12.5 inches with the compensator fitted.
• Overall length is 35 inches with the buttstock and 25.5 inches without it, the difference the detachable stock makes.
• Weight is 12 pounds, which keeps the gun steady and recoil mild.
• The buttstock is detachable American walnut, which comes off to shorten the gun for a case or safe.
• Up front is a walnut vertical foregrip, the classic 1927 support-hand layout.
• Sights are a blade front with an open, adjustable rear, so the point of impact can be tuned to your ammunition.

Frequently Asked Questions

How long is it with the stock removed? Auto-Ordnance lists this model at 35 inches overall with the buttstock and 25.5 inches with the buttstock removed.

What magazine comes with it? It ships with one 20-round stick magazine.

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.

Buy the Auto-Ordnance Thompson SBR .45 ACP, 10.5-Inch, Detachable Walnut Buttstock

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.