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45 degree selector and triggers compatibility

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There had been reports of the 45 degree selector's compatibility with couple of triggers, so I will elaborate this issue a little.

So far, we know of two triggers that seem to have issues with the 45 degree selector: AR Gold, and Wilson Combat's TR TTU (the original TTU works fine).  To this, I have to add that these triggers have heretofore caused issues with the 45 degree selector, but they may not be ALL incompatible.

We do not have an AR Gold trigger, so this finding is limited to the TR TTU.

The first generation of TTU used to have set screws on the bottom to allow some height adjustment, subsequent models have springs, the only way to “adjust” them is by clipping off coils. Without these springs, the trigger will fire even when the selector is on SAFE. With them installed, they push the entire housing, and the trigger’s rear tail up and puts it in contact with the selector center.

This isn’t a problem with 90 degree selectors, as the rotation is a full 90 degrees, the travel is too long for the trigger to complete a rotation to FIRE. With a short throw selector, the tail touches the leading edge of the flat area of the selector and can rotate it out of detent engagement.

Partially this has to do with the angle the detent hole are cut, we’ve since changed over to a different angle that allows much less movement when the detent is engaged. When the lever is on SAFE and perfectly parallel to the bore, the trigger cannot rotate the selector out of detent engagement. When there’s a light movement in the selector, the trigger has a better chance of rotating it out of detent engagement.

Also at fault is the taller trigger “tail”. When a manufacturer improves a trigger, by definition it is already not in original specs. Our selectors are designed for in spec receivers and triggers, as long as both are close enough to the original specs, the tolerance stacking issue is mostly a moot point.

Our favorite triggers are the Geissele triggers, all versions of Geissele are compatible with the 45 degree selectors, as well as factory, RRA, JP, KAC, etc.

Since being on the market in late 2010, we've had but two or three reports of incompatibility, so this is definitely not a wide spread symptom.

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The problem we identified with the AR Gold trigger was the trigger's rear extension is too tall.  The trigger's rear extension interfaces with the selector's middle, flat section.  Our middle, flat section measures 0.240, a cast selector's mid flat section is about 0.230.  The milspec is taller than both of these.  We've reduced the center diameter couple of times to make it more compatible with aftermarket triggers that deviate from Colt specs, in the case of the AR Gold trigger, it's just too much.

Below, left is my receiver with an RRA trigger, hammer uncocked.  Right is an AR Gold trigger, hammer uncocked.


The trigger's rear "tang" is super elevated, and can cause problems with either the 45 or 90 degree selector.

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Many of you know we've been talking about playing with the throw distance for months.  We've made close to a dozen prototypes with various throw distances.

The reason for this is simply the inevitable slack exists when the selector is rotated to either FIRE or SAFE.  The detent holes must necessarily be slightly larger than the detent itself, or the detent can't go into the detent holes. The detent holes must necessarily be slightly larger than the detent itself, or the detent can't go into the detent holes.  This slack and angle of the detent holes are the reason for the 2 to 4 degrees of movement when the detent is engaged, with the selector rotated to either FIRE or SAFE.  Though with the latest development we did on the detent groove and detent holes, the slack has been reduced, we are always looking for ways to further improve things.

With a 45 degree selector, 4 degree of movement each way is more exaggerated than it is on a 90 degree selector.

With triggers that are spec, or close to spec, the 45 degree selector cannot be rotated from SAFE to FIRE by pressing on the trigger, the experiment with 50 to 55 degree selectors has nothing to do with this issue that's really a tolerance stacking problem caused by triggers that are too beyond spec measurements.

No decision has been made on these longer throws.  We're of the opinion that 45 degree throw is the optimum throw arc for a short throw selector.  HK, FN, and other manufacturers apparently feel the same way, for their throw arcs sometimes are even shorter.

In other news, a short throw M16 selector is also now in development  ;D

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