CNP (Castle Nut Punch) is a dedicated castle nut staking punch, while it can do double duty as a golf tee or Van Helsing's EDC, it was designed for a singular purpose, that is to displace material from an AR15/M16 end plate into the castle nut's staking notches.
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.
We 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.
Special thanks to Lander Salzberg at
1000 Ships for his input. Lander is a good friend, and recognized as one of the best builders of high end ARs.
Proudly designed and made in the USA.
NOTE:
* CNP is an instrument, it should be maintained, i.e. oiled now and then.
* Know your end plates. We advise 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.
Below is a picture of staked castle nut after 3 strokes with a mallet using CNP. Also visible is a smaller dimple that was started but abandoned because it's slightly off, the eventual staking punch blows were much better placed. Stakings don't have to be pretty, they just have to work.
For staking castle nuts, below is an excellent video from our friend NSZ85:
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