CN5F (Castle Nut, A5, Forward Controls) is an extended version of
CNF we've been making since 2018. CN5F is designed specifically for the
superb Vltor A5 system, CN5F is 0.1" longer, and is as long as we can
make a castle nut while ensuring backward compatibility, and the stock's
ability to fully collapse on Vltor's RE-A5 and our RE5F. Note: not all
stocks will fully collapse on A5 compatible REs. For more information
on the differences between RE-A5, RE5F and RE10/A5SR, please follow
this link: https://www.forwardcontrolsdesign.com/Vltor-RE-A5-vs-RE10-A5SR_ep_78-1.html
aims to cover as much of the threaded area of a receiver extension (RE)
as possible. It could be made longer, but it will run into backward
compatibility issues with some REs' timing when installing the castle
nut and end plate on the RE. CN5F is made specifically for the Vltor A5
system, and it will allow even the longest carbine stocks to fully
collapse on RE-A5 and our RE5F. While CN5F will also work on standard
TDP spec length RE, the additional length of the castle nut will prevent
the carbine stock to fully collapse.
Other than its length, CN5F shares common features with its smaller brother, CNF.
TDP spec castle nut is a simple and robust fastener that is almost
perfect for the job it's tasked to perform. Over the years, we've
consistently come up with two minor gripes, first is its staking notches
seem rather shallow and short, second is we don't enjoy using the
castle nut's wrench notches as serrations (our fingers invariably find
their way to these sharp cutouts) to rotate it towards to the end plate
while installing it.
CN5F (Castle Nut, Forward Controls) is based on the TDP spec castle nut, with couple of changes:
1. 0.1" longer.
Staking notches angle changed from 45 to 30 degrees, this results in
longer (25% longer than TDP spec) and deeper notches than found on TDP
3. Number of staking notches increased from 3 to 4,
spaced equally on the CNF. The castle nut is to be staked in two
places, we're not advocating staking in more than two places, CNF's 4
staking notches mean that, at all times, 3 will be visible and available
for staking, it simply gives the user more staking location options.
Coarse serrations on the wrench side of the nut, a single use feature
to make it easier while rotating the CNF towards the end plate.
is our opinion that a castle nut should be staked per TM, CNF's and
CN5F's longer and deeper notch reinforces the belief, that once
installed and staked, it will not loosen without the user's deliberate
action. We like the idea of quick detach, but some things on an AR are
meant to stay put, and considerable effort was made to ensure that by
the original designers. CNF and CN5F are a continuation and evolution
in that direction.
CN5F is billet machined in 4140 PH steel, and
black nitrided. As with everything Forward Controls Design produces, it is
proudly made in the USA.
FCD would like to thank Ash Hess for letting them use parts of the Army/Air Force /
Navy TM for CNF's installation instructions, on the back of the card.