I believe if it is marked as a pistol from the factory, even if it has an arm brace, it is still considered a pistol so no SBR stamp would be required. Now, if you put a actual stock on it, not an arm brace, then it would become a SBR. Before they went out of biz Remington had something similar and it came with the arm brace and was called a bolt action pistol w/arm brace.