After much head scratching I decided to post step by step
directions rather than a video, besides I am a better writer than a movie star.
In 1964, or there about, Winchester decided to replace the
model 12 with a firearm much cheaper to produce, the 1200 was the result. Evolution
took its toll and the 1200 became the 1300 as well as a few semi autos based on
the same design and receiver.
The Winchester 1200-1300 serves its purpose well; an
inexpensive pump gun, and there are a bunch of them out there. Rarely will you
see much problem with them except double feeding. The problem is the plastic
throat where the magazine tube goes into the receiver. The original throat was
a two piece model and it does have a tendency to separate and allows two shells
to be released into the receiver when the shotgun is pumped.
The fix is replacing the two piece with a one piece. To do
this a few special tools are required one is what I named Thor, a large heavy
wood hammer with a leather face. The other is a slide hammer type rig designed
specifically for replacing this throat.
The slide hammer is simply nothing more than a round piece
of steel with a hole bored through it large enough to allow the mag tube to fit
closely, but not be sloppy. The 12 gauge and 20 gauge is the same size so only
one slide hammer is needed.
Disassemble the shotgun including removing the stock. The
whole process is hand held, no vise.
Install a slave magazine cap to ensure there is no sling
stud on the cap, ensure the cap is tight, put Thor to work by hitting the mag
cap. This will drive the plastic throat into the receiver. Continue driving the
mag tube into the receiver until the plastic throat clears the receiver. The
two piece throat will usually fall out when the mag tube clears the
receiver.
If you are replacing a one
piece throat it is not necessary to remove the mag tube from the receiver, but
replacing the two piece requires a new mag tube be installed as well.
If you are installing a new tube, remove the mag cap and
install the slide hammer, re-install the mag cap and begin striking the slide
hammer against the mag tube. The slide hammer will do the work, you just supply
the power.
Gradually the mag tube will inch its way out of the
receiver. Continue driving the tube out of the receiver.
If you are replacing the two piece throat with a one piece
throat you will need a different magazine tube.
To install a new tube install the mag cap align it in the
mag tube opening and put Thor to work. Commence driving the mag tube into the receiver.
You will drive the tube all the way through the receiver. Once the tube is
through the opening, screw the new plastic throat onto the tube, re-install the
slide hammer and you will drive the plastic throat back into place. The throat
should have no gaps between the throat and the receiver.
The new throat is now installed. Hope this helps!!