SLCF (Selectable Lower Components, Forward Controls Design) is our answer to many veteran AR users and builders. Given the variety of superbly designed, non-factory components in the market space, the LPK as we know it seems to be of a mindset of early 2000s. While a typical LPK will contain pins, detents and components that seem to be in a perpetual state of shortage in our parts bin, there are also parts that don't fit our needs and are completely unused. The idea of an one size fits all LPK is ill suited for many experienced AR owners.
As my friend Nate Schultz (NSZ85) is fond of saying, no is always an acceptable answer. So we incorporated "absence might be a better option" into the SLCF. SLCF has "Do not include" is the default, and starts with a base price of $0 (nothing included), you can add what you need.
SLCF is essentially a collection of lower parts all on one convenient page. Last available in 2020, the 2025 updated SLCF has more options (triggers, ESF-H and CNF varieties) and fewer in other areas (stocks, buffer springs).
NOTE:
For the safety, ASF is the ambidextrous safety where you choose the left and right lever. SF is the non-ambidextrous, single sided safety, choose only a left lever (if you're a right hand user) or right lever (if you're a left hand user).
SF-50 and SF-90 are reversible.
FOR SF-50Q AND SF-90Q ONLLY:
Though SF-50Q is reversible, i.e. the lever can be on either side of the receiver, do note that Q (offset) levers are side specific. When ordering SF-50Q levers, the drop down menu offers either the right hand version with the lever on the left, or the left hand version with the lever on the right.
While a left Q lever can be installed on the right side and vice versa, the way the Q lever is offset will differ if a left Q lever is installed on the right side, or when a right lever is installed on the left side. The way the Q lever is designed to function on the ASF is with the offset biased towards 12 o'clock when the safety is on SAFE, but we've seen users do the opposite, where the offset is biased towards 6 o'clock, which is the way HK weapons safety levers are arranged. There is no wrong way as long as it works for the end user.
Left: ASF lever. Right: HK MR556/HK416 lever, notice the ASF's lever is biased towards the top, while the HK lever is off axis towards the bottom.
SF-50Q or SF-90Q shown below with the Q lever offset towards the bottom, or HK556MR/416 style:
The purpose of the top offset of a Q levers is for a 90 degrees ASF or SF safety, the lever is closer towards the rear (butt stock side) when the safety is on FIRE/SEMI, this offset allows most users to access the lever with their thumb without breaking their grip. For an ASF or SF with a 50 degrees throw, the Q lever serves a different purpose. The Q lever is off axis towards the top when the safety is in the SAFE position, when rotated to FIRE with a 50 degrees throw, the offset places the lever higher up, this has the effect of putting more distance between the lever and the user's extended trigger finger which can inadvertently / unintentionally lifts and rotates the safety back to SAFE.
Additional grips and carbine stocks can be found on related items shown below the description.
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