Forward Controls Design Castle Nut Punch Black CNP Caslte Nut Punch. Machined from D2 steel heat treated and finished in black oxide CNP has a broad / flared top to provide a stable striking surface. It also has widely spaced and aggressive serrations to ensure the user's hands gloved or ungloved will not lose their grip. CNP was originally designed to have a rectangular tip it was subsequently abandoned and we went to a round tip. A rectangular tip can be very unforgiving of tip placement and the sharp edge and corners of a rectangular tip can be rapidly and more easily deformed and most importantly we don't see any advantage of a square stake over a round stake a conventional punch produces. Given the host of problems a rectangular tip has and what it brings to the table (nothing) it was an easy decision to redesign CNP to have a round tip. Forward Controls Design produced a handful of candidate tips with different sharpness and angles and decided on 52.5 degrees angle with a sharp tip. Each prototype was tested for ease of use and effectiveness of the angle and sharpness. The design also changed from a rather long and larger diameter body to one with a shorter length smaller diameter. With the original design we believed the larger contact area would obviate the need for serrations. Since the redesign now has a smaller diameter serrations were added to provide positive grip on the CNP. Progression of the CNP. Left to right (left 5 samples): original design with longer length and larger diameter heat treated new design with shorter length and small diameter (dark brown in color prior to coating) and production candidate with shorter length small diameter and serrations. NOTE: CNP is an instrument it should be maintained i.e. oiled now and then. Know your end plates. Forward Controls Design advises that you find out how your end plate is treated. TDP spec end plate is made in 1018 or 1020 low carbon steel and for good reasons. Nitrided end plates are very difficult to stake we avoid nitrided end plates when possible it's exceedingly and unnecessarily hard and may blunt the punch's tip prematurely. If you're not familiar with staking castle nuts please consult or bring it to a qualified gunsmith. If you ugga dugga and wield the mallet like Thor you can risk punching through the end plate and damaging your receiver extension. We are not responsible for the consequences resulting from misusing and/or abusing of tools. Specifications for Forward Controls Design Castle Nut Punch: Manufacturer: Forward Controls Design Color: Black Finish: Heat Treat Fabric/Material: Steel Gun Make: AR Platform Gun Model: AR-10 AR-15 Features of Forward Controls Design Castle Nut Punch Flared top for consistent force Round tip aids in the staking process Simplifies castle nut staking Package Contents: Forward Controls Design Castle Nut Punch What firearm models does the manufacturer say Forward Controls Design Castle Nut Punch is compatible with? The manufacturer suggests that Forward Controls Design Castle Nut Punch is compatible with AR-15 AR-10Forward Controls Design CNP Caslte Nut Punch: Castle Nut Punch Black