A firearm suppressor includes a hollow outer can having an interior-threaded proximal end and a radially closed distal end with a bore, a barrel nut having a barrel bore and an outer-threaded distal threading to the can, and a baffle. The baffle has an intermediate wall with a bore and extends outward to the can interior to prevent fluid passing across other than through the bore. A proximal baffle wall has a bore aligned with the other bores and is shaped to secure to the barrel and extends outward not as far as the outer can interior to permit fluid passage. The baffle is shorter than the can's interior length to have the can, the nut, and the baffle define a plenum extending from the proximal end portion to the nut so that the proximal baffle wall directs fluid from the barrel backwards as a muzzle brake.