Gap between the receiver and selector levers

[Battle Arms Dev]

This is a subject that comes up now and then, so we'll stick this here to serve as general information, as it applies not only to our own selectors, but all selectors.

There is a gap between the underside of the selector lever and receiver wall.  The extent of the gap is a matter of receiver thickness.

We took measurements from couple of dozen receivers before deciding the length of the selector center.

What it comes down to is the thickness of the receiver. The milspec thickness is .880 +.015 -.002, or .878 to .895. We based our selector axis off one of my Colt SP1s, which is 0.898 and on the thick side.  Even within the same company, there are variations.

This is a factory selector on an AR10

This is the prototype selected for production, after we've reworked the length of the selector center.  The difference in amount of gap between the left and right is 0.01, the reference receiver is a Colt SP1.

[img width=810 height=297]http://i75.photobucket.com/albums/i314/Duffypoo/Mod0protrusionsonColt1.jpg

CASS-3P, M16 (picture taken before our patent paperwork was filed to mask the patent pending dovetail interface)

[img width=810 height=850]http://i75.photobucket.com/albums/i314/Duffypoo/bothleversfromunderthereceiver.jpg

Colt, Bushmaster Armalite, DPMS, LMT and KAC are all pretty well within specs. POF and another billet lowers are notably thicker, at 0.905 and 0.911, while Olympic Arms are notably thinner than specs.

There's NO way to make a safety selector and have it fit flush with all brands of receivers, as mentioned, even within the same manufacturer there's slight changes.

The same ambi selector that fits flush on a Bushmaster, LMT, and KAC will almost be too tight for a POF. With a standard, non-ambi selector, this isn't an issue. If you haven't noticed, the axis usually sticks out a little on the right side, while some don't. This can be a problem for ambi selectors, too much protrusion on either side, it won't be as low profile as can be, and the lever will pinch your finger when you rotate the lever from Safe to Fire while its extended in the "finger outside the trigger guard" position (this is actually somewhat unavoidable, we just try to minimize the pinching).

There is no problem with the lever sticking out and not sitting flush (it will never be flush, the original Stoner design calls for a gap between the lever and the receiver, and for good reasons).  In terms of rounds fired, eight M16 with our selectors had 100K rounds through them in less than four months without any failure.  Semi auto selectors have far more rounds fired, as there are more semi auto selectors in the hands of users :)

[Battle Arms Dev]

With the CASS-3P family selectors, M16 and the upcoming semi auto, the selector center will protrude a tiny more than the current semi auto 45 and 90 degree selectors.  The reason is the female dovetail interface is on the tip of the selector center, and there must be enough clearance to ensure the male dovetail interface, which is on the  bottom of the CASS-3P lever, does not come in contact with the receiver, or bind when there's debris between the lever and the receiver.

The selector center must be sufficiently long to accommodate various receiver thicknesses from different manufacturers.  If Colt made all the receivers, we'd be able to make ours more form fitting, alas the thicknesses are all over the place, making compatibility a serious issue we must address.

That the levers do not sit flush with the receiver isn't necessarily a drawback.  Levers that protrude further out have the effect of extending their usable purchase.  On the flip side, the trigger finger side lever can pinch your hand while it's being rotated from Safe to Fire, but in our experience, even when the gap is very small, pinching can still take place.  It is then quite unavoidable, and the gap isn't the culprit, the 90 degree legacy throw is responsible for that.

One might argue that such gap doesn't exist for SIG, HK, FN, etc., this may be true, but remember these manufacturers do not have dozens of other companies making receivers for them, all with slightly different dimensions  :P

[98Z5V]

There's NO way to make a safety selector and have it fit flush with all brands of receivers, as mentioned, even within the same manufacturer there's slight changes.

Roger, IMHO, it's better that they're not flush, in the least.  I've had a few standard selectors "drag" on the receiver during a build, and they get clearanced.  It's a pain, but necessary.

I love the fact that yours have a little stand-off, which is even more important if you coat your receivers with anything (Cerakote, Aluma-Hyde II, Duracoat, Krylon, etc.). 

You've done extremely well in the design, and I truly hope there aren't people out there that have an issue with the lever not being flush.  If that's the case, and they are out there, then they're just not understanding the intended design.

Excellent piece of equipment.  <thumbsup>

[Battle Arms Dev]

Thank you!

Very few people have.  We've known that some might.  Speaking from personal experience, going from a single lever selector to an ambi, the gap is noticeable with any AR ambi selector because there is none with the single lever selector.

The extra stand off distance is actually, albeit unintentionally, helpful, as it pushes the levers out a bit more and provides a bit more usable leverage :)