Winchester Repeating Arms 1400 (Historic Manual) - Manual (Page 6)

2. Unscrew and remove the valve cap
assembly from the magazine tube
(Figure 2).
3. Slide the forearm forward and off
the magazine tube.
4. Place the forearm against the barrel
as illustrated and slide the forearm
forward over the magazine bracket
(Figure 3). The magazine bracket on
the barrel should be completely hidden
by the forearm.
5. Carefully place the breech bolt in
the forward position as previously
instructed.
6. Holding the barrel-forearm
combination in one hand, insert the
magazine tube (4"A") into the opening in
the rear of the forearm. Slide the barrel
and forearm together back as far as it
will go. There should be no space
between the front of the receiver and
the matching shoulder on the barrel
(Figure4).
7. Check to insure ejector is in proper
position in barrel extension cut.