The First Phasers. The main Story
Let us study this model from "head to toe," starting at what some would call the "business end," the front of the phaser, right at the tip of the emitter. The best of these tips appear to be machined acrylic cut into a long tapering cone shape and tapering to a blunt end. The crudest of these tips was simply a piece of plastic tubing mounted into the barrel/muzzle.
A few of the working models had tips that were drilled out with two sizes of holes with the rear one large enough to hold a grain-o'-wheat light bulb installed for a lighting effect that could fire out a smaller hole drilled out to the front of the tip. There is one visible in the "Making of Star Trek" paper back book.. These lights are believed to have been installed to aid the special effects artist who would then key in on these lights when they drew the animated beam of a phaser firing.
Current custom is to leave out tip lights, for example the phaser in "Star Trek - The Search For Spock" had no tip light. Animation is charged by the frame and an actor firing for three seconds is cheaper than a ten second blast, plus he might be aiming it wrong when he does fire or worse, fire at all the wrong times. (See a note about bloopers, later in this article.)
Next, behind the clear tip, is the machined aluminum muzzle. So traveling back along the tapering tip, we come to a flat section at right angles to the tip. This is a recessed cut into the face of the muzzle about 1/8" deep and is a 3/4" flat wide section with the clear tip bored right into the center.
The number two version of this muzzle is the same as the first one but with a cone cut in place of the flat section around the clear tip. It looks a little like a flashlight reflector, which may explain why there is only one seen so far. The people on the show may have felt this appeared a little too much like a current day flashlight to use on the show.
winging around up from this recess, but still on the muzzle we then find there are several levels of rings that look like three steps. Then a longer area or flatter section of rings, or cuts, that look like rings. Moving back we come to a center ring which is the largest and widest ring. This center ring has sections that are divided by a mix of flat plane sections cut into a lined rounded part of this center ring. There are about six to seven fine lines cut into the rounded sections between the flat cuts, and these run all around this center ring. There is a flat section, then a section with lines followed by a flat section, alternating these areas all round this part of the barrel's ring.
An added feature on the "hero" model of these muzzles is that the center ring is a rotating ring. Possibly this mechanical effect is intended to suggest an adjustment feature for the actors to use in a scene where they needed to select a special setting, ranging from wide beam to a laser point. We never see this demonstrated though there are several scenes where Cpt. Kirk does place his forefinger alongside the muzzle. Was this a modern day "finger off the trigger" pose or...was he intending to adjust the beam width or setting? And one early scene had Scotty cutting exactingly through a bulk head with a tight beam.
There was a special feature involving the clear pistol tip and this "hero" muzzle. As the phaser one is loaded into the pistol body, the front of the phaser one engages a pocket in the pistol body then has to push forward as it is set in. This socket is connected to the tip and spring loaded so that when the socket is pushed forward, the tip telescopes or is pushed out of the muzzle. When the phaser one is removed, this action would, of course, retract the tip. At rest, without a phaser one, the clear tip was retracted in the pistol body muzzle.
As a point of interest to nitpickers and fans of bloopers, there are a couple of scenes where you can see that this part failed to engage or failed to hold and the tip pocket has slipped under the phaser one and the tip has withdrawn into the muzzle. Check for this in a scene from "The Conscience of the King" and other episodes.