<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2009) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2009) (Learn how and when to remove this template message) </Td> </Tr> <P> A powder - actuated tool (often generically called a "Hilti gun" or a "Ramset gun" after their manufacturing companies) is a type of nail gun used in construction and manufacturing to join materials to hard substrates such as steel and concrete . Known as direct fastening, this technology relies on a controlled explosion created by a small chemical propellant charge, similar to the process that discharges a firearm . </P> <P> Powder - actuated tools come in high - velocity and low - velocity types . In high - velocity tools, the propellant charge acts directly on the fastener in a process similar to a firearm . Low - velocity tools introduce a piston into the chamber . The propellant acts on the piston, which then drives the fastener into the substrate . (The piston is analogous to the bolt of a captive bolt pistol .) A tool is considered low velocity if the average test velocity of the fastener is not in excess of 328 ft / s (100m / s) with no single test having a velocity of over 354 ft / s (108m / s). High - velocity tools may not be made or sold in the United States, however some made decades ago are still in use in the shipbuilding and steel industries . The main manufacturers of powder actuated tools are Ramset, Hilti, Powers / Dewalt, Tomarco and Simpson Strong Tie . </P>

Powder actuated tools are similar in operation to which other device