as winston churchill once remarked, this is not the beginning of the end, but it is the end of the beginning for the time being.
i have finished rough shaping the lower receiver, and i have finished epoxying the stainless steel clads to the wooden core of the lower.
to my eye, at least, the lower looks very much like an ar-15 lower, absent the buffer tube nut at the rear of the receiver. --
caption: the laminate plug, with pistol grip expoxied and pinned to the laminate. you'll note the relief cuts at the rear of the receiver & pistol girp, for the upper part of the hand.
caption: epoxying the stainless steel outer clads to the plug, using e6000 epoxy/adhesive. the e6000 is interesting stuff, it stays kind of plastic even as it cures. this is the way it is supposed to act, and it aids in carrying vibration and shock loads, ... , according to the literature i've read.
the stuff on the upper receiver is carnauba wax. for some reason, epoxy does not stick to wax. so, to keep from inadvertently welding pieces together when epoxying, it is best & prudent to wax any part that you don't want stuck fast in the process.
note: all action screws are in place, and fastened tightly, to assure good adhesion, and to assure that the clads do not "slide" under clamping. it seems to have worked.
caption: the corners of the clads relieved to match the relief cuts in the laminate plug. no "sharp corners" wanted right there.
caption: i don't know that the "plywood gun" looks sleek, exactly, but getting into final trim is looks a lot better, and easier to see its function, than when it started life as a solid wooden rectangle.
two .152--154" diameter slave pins hold the trigger and hammer assembly in place. if you'll look at earlier posts, you will see that the sear engagement is very good. here, the hammer is held in battery, the nose of the trigger fully engaged in the hammer sear notch, solely by gravity holding the trigger with the trigger nose "up" pull the trigger, and the hammer moves.
i could not have done it any better if i'd tried. i will thread the end of the pins, and hold them against the receiver in tension with nuts at either ends of the pins. they shouldn't be subject to any drift at all.
there you have it.
the "live links" at the bottom of this piece will connect you to previous articles. i don't know if any of you late to this story have noticed, but even though the receiver is the size of an ar-15 receiver, the magazine well in the "plywood gun" is the dimension of an ar-10 magazine, and it, in fact, holds an ar-10 magazine.
if you find this interesting, you can go back and read the reasons why.
update, 01.29.2013 fabrication of the trigger and hammer pins. the trigger group pins in an ar-15 generally have grooves cut in them, and are kept from "drifting" out the side of the receiver by spring tension on those grooves.
well, i lack the resource to groove pins, for some odd reason. it's kind of a reflection of a misspent youth, i guess.
at any rate, i found a 5/32nd's (that's .152-.154" in ar-15 speak) mild steel rod to use as a pin, but, had no way to secure them in the receiver. so, i decided to thread the rod, and put nuts on the end to hold them in place.
i went to napa, and got a 10-24 threading die, but, it did not fully form the threads, being a bit large. so, i got an 8-32 threading die, and it didn't want to feed the stock through it. just for shits and giggles, i ran the 8-32 die over the threads cut previously by the 10-24 die, and out came perfect threads. by "perfect," i mean threads that would accept 8-32 nuts.
caption: 10-24 & 8-32 thread dies, and the mild steel rod.
caption: run the rod through the die, and cut the threads. works just the way it supposed to, if you take care to get the die started properly.
caption: a section of rod, threaded at both ends. this is the way i "gauge" the proper amount of threading. no, it isn't rocket science, for the most part.
caption: this is the hammer pin. when the trigger group gets installed into the trigger well, this pin will mount the hammer. i suppose that is whey it is called the hammer pin, you suppose. again, none of this is rocket science.
the screws will be tightened moderately, and if they show any tendency to loosen, i will simply "double nut" them. we'll see. end update.
john jay @ 01.28.2013