With the new 45/90 degree compatible receivers available, and more from Spikes Tactical and AXTS already in production, we should elaborate on the 45 degree selector's development history.
The 90 degree selector (what we deem, and therefore call legacy selector) is something of a mystery to us. We are hard pressed to think of tangible benefits to a 90 degree throw, other than requiring the shooter to be deliberate of his selector action, as the throw is longer than necessary.
The long throw notwithstanding, it also introduced another problem: when the selector is set to Fire, the lever points straight down and creates interference with the trigger finger.
With our semi auto ambidextrous selectors, we came up with levers of various geometry, length and thickness to reduce the interference, but it is impossible to get around it altogether. This is a design constraint, as it is based on the legacy 90 degree throw selector.
There's typically no problem switching the weapon from Safe to Fire, the problem has to do with the reverse (switching from Fire to Safe), it will require the shooter to shift his grips. With an ambidextrous selector, the awkward motion is mitigated by the shooter's being able to use his trigger finger to manipulate the trigger side lever, but there is no denying the ergonomics of this arrangement are of dubious quality.
For an M16, the ergonomics shortcomings are even worse.
For decades, other platforms have had the short throw selectors. HK, SIG, Beretta, FN, and lesser known military rifles have had them since the 60s.
The short throw arrangement certainly isn't new on these platforms.
We made the short throw selector for the AR15 (and soon M16) platform. The result is fairly predictable: much faster selector manipulation, no shift in grips during lever manipulation from any direction, much reduced interference to the trigger finger.
We did run into a problem: liability. At 45 degrees, the position indicator groove no longer points to Fire on a standard receiver (at 12 o'clock). We thought of everything possible to get around it, and in the end we had to make our 45 degree selector incompatible with existing receivers by pressing a stainless steel pin block into the selector center, to prevent its use on a standard receiver. The idea is that the short throw selector needs to be used on a properly marked receiver, the standard receiver's Fire marking is inadequate.
Note on the stainless steel pin block: the sole function of the pin is so the 45 degree selector cannot be inserted into a non-45 degree compatible receiver. The removal of which will constitute unauthorized modification and void the warranty. We do not publicly or privately suggest or recommend such modification.
The 45/90 degree compatible receivers are different in two areas: new Fire engraving at 68 degrees so the marking is suitable for both the 45 and 90 degree selector, and a notch cut in the left side of the receiver selector hole. This gives the receiver the unique ability to accept either the 45 or legacy 90 degree selector.
45 degree selector in action. Note the shooter's grip never moved during selector manipulation
More to come...