Okay, here is a little update on my earlier post:
So building on the excellent development showing that the caulking putty becomes flowable at higher (low temp glue guns) temperatures, I decided to build a plunger adapter for the glue gun I was using. The trough tube is K&N Metals 15/32" OD brass tubing, chosen because normal size glue sticks are 7/16" diameter, and I wanted the tube to be nice and snug inside the rubber boot. The plunger rod is a piece of 3/8" aluminum rod, though I would strongly suggest against using it for this, is at makes the other steps more difficult. The plunger head is simply a section of 7/16" OD brass tube soldered over a section of 13/32" tube, then secured through haphazard means to the aluminum. I will probably redesign this shortly.
So the trough tube is cut and flayed open, then placed inside the rubber boot that the glue sticks normally sit in. The rod is placed in the back of the gun.
Once assembled, simply load some putty in to the trough and press the plunger down.
To make the darts, use the hot head of the gun in to the blanks, just as if you were going to insert a metal weight. But don't do that, because that would completely ruin this whole project.
Now simply press the plunger down and dispense the molten putty until the cavity is filled.
Finally, add the felt tip making sure to have good contact between the putty and the felt.
Last step: Complain to self about using random "samples" of foam that had not been properly straightened nor cut well.
Post Script: Man, the red foam is WAY less tolerant of higher temperatures than the beige was. Time to pull out some of the white foam while we wait for the pink to arrive.