ESF-L (End plate, Sling Adapter, Forward Controls Design) is a drop
in end plate replacement for the AR platform (both 223 and 308 spec).
Featuring three quick detach sling swivel sockets (two side, and one
rear facing), when used in conjunction with a castle nut, ESF will allow
retractable carbine stocks to fully collapse. SOPMOD and B5 Systems
Bravo stocks will fully collapse with a rear facing QD swivel installed,
other carbine stocks must be closed on the #2 position on the RE (#1
position being fully closed) if a rear facing QD swivel is present.
The ESF has
rotation limited side facing sockets. The rear facing socket has no
limiters, as the receiver extension effectively limits the swivel’s
rotation. From late 2018, non-rotation limited side QD socket option
has been deleted, all ESF versions have rotation limited side facing
As is FCD's practice, ESF’s shape is dictated by its functions. In
order to accommodate the rear facing socket, and fill one of the design
requirements that ESF must be able to use stakable castle nuts and allow
the carbine stock to fully collapse, ESF has a slight increase in width
on the sides, and small openings on the top of the sockets housing.
These design cues do not affect ESF’s structural integrity, and mostly
go unnoticed by users, they merely reflect a paradox, that it can be
quite complicated to create a simplified design. A seemingly simple
product can often be more than meets the eye.
Aesthetics were never a part of the stated objectives for ESF.
Nonetheless, ESF, like similar products before it, effectively lengthens
the carbine receiver’s rear and gives it a silhouette reminiscent of
the classic AR10/SR25. We’ve long considered the AR carbine’s rear
seems to be abruptly terminated, which leaves a gap between the end
plate and the carbine’s retractable stock. ESF fills the void and, the
classic AR15/M16 lines flow far better with it. Even though we take a
dim view of fashion firearms and components, we can still appreciate
aesthetics, especially if they stem from the design’s functions.
ESF-L is made from 7075 aluminum, black anodized at 0.39oz.