Safety rotation and detent engagement

ASF was conceived in late 2018, and after a lengthy development, went to market in May of 2020.  Of the time and resouces we expended in its development, ASF's rotation and detent engagement took the lion's share.  

We had no fewer than a doezn prototypes with variious detent hole depth, angle, detent groove depth, angle, and shoulder depth.  The result is in the ASFs smoothness in rotation and positive detent engagement.

The way an AR15 or M16's safety rotates, and the manner in which detent terminates the safety's rotation in the detent holes can be affected by external factors, such as the detent, safety spring, grips, and lower receiver.  We've seen lower receivers with out of spec safety detent/spring hole that woudl produce a mushy rotation and weak detent engagement, it is rare but does happen.  

Chief factor among these is the grip, namely, the depth of its spring hole, on the right side of the grip.  The deeper the groove, the less spring pressure is being pushed against the detent which enages the safety's detent holes and groove, the rotation feels soft and mushy, and detent engagement feels anemic.  Conversely, if the detent hole is too shallow, too much spring pressure is pushing the detent, this results in a stiff rotation, and can prematurely wear the detent.

The A2 grip's TDP spring hole length is 0.67, +/-0.01.  Many well made 3rd party grips largel adhere to the specs and tolerances, but not all of them.

Below is a small sample size of grips we have handy, we mesured the length of the safety spring protrusion.

Left to right:

B5: 0.245

BCM: 0.241

Magpul MOE: 0.231

SIG: 0.2480

Colt (cut down for an experiment): 0.0206

Of these grips the sample Colt A2 grip will produce a mushy rotation and weak detent engagement.  

To be sure, a safety that has a mushy rotation and weak detent engagement is still functional, as long as the safety isn't easily rotated out of position, the safety is functional.  Users may have different expectations of how a safety should rotate and engage the stops, beware the safety is but a part of a system, and works with other parts to perform its task, a perceived mushy rotation and detent engagement almost always means it's being affected by the parts it interacts with.