Details
The Winchester Model-12 must have the bolt closed by the action slide before the slide bar can be slid out the front of the frame for takedown.
If the bolt was not closed by the slide, then there is a serious breakage, and I do mean serious.
Most likely, the bolt failed to stay closed because the "bolt retaining lever" has jarred free, is loosely-fit, or the combination of some wear of it and the retaining notch it uses in the frame.
This wear condition is not always a problem to fix, but the longer the situation repeats, the worse it may get.
If the bolt has jarred/slipped loose and gone somewhat to the rear, instead of being in the normal closed position, the frame may be hit face down against a padded surface to inertially drive the bolt to the front of the frame, and then you can manipulate the tail of the bolt up into the locking notch by pushing up on the carrier and using it to push the back end of the bolt up.
That is the position necessary for the slide to be able to engage the bolt and operate the gun.
Now what do you do?
Since the bolt will try to drop back down until the slide is inserted fully into place, have the barrel assembly on the frame but without the slide handle pulled back into position, but have everything else in line so you can pull the slide into position while you push the back end of the bolt back into the frame locking notch.
Finish the assembly.
Remember to have the parts fixed to allow normal takedown and assembly that a Model-12 should provide for years to come.
Is that helpful?
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