On the 727, starting with the cargo door closed, when you actuate the cargo door handle the door moves up a bit above it's lip before the door actually opens, thus technically the cargo doors are plug type.
Myself and the Aircraft Manual respectfully disagree. The upward motion is only necessary for the locks to clear above the locking components on the side of the door.
2 . Passenger/Crew Doors
A. Forward Entry Door
(1) The forward entry door is on the left side of the airplane. It is
an inward-outward opening plug type of door which can be operated
from inside or outside the airplane.
4 . Cargo Doors
A. ALL EXCEPT 727-200;
There are two cargo compartment doors on the lower right side of the
fuselage, one serving each cargo compartment. Both doors are hinged at
their upper edges and open inward. Access panels are provided in the
external skins of the cargo doors, to enable manual release of the cargo
door latches if the operating mechanisms fail. Except for slight
differences of shape, both doors are identical in design and operation.
Access to the aft cargo door is covered by the trailing edge of the wing
to body fairing. The rear end of this fairing is a separate section
mounted on rails so that it can slide aft to allow access to the cargo
door.
B. 727-200;
There are three cargo compartment doors on the lower right side of the
fuselage. The No. 1 and 2 cargo doors are hinged at their upper edges
and open outward. The No. 3 cargo door is a plug-type, inward opening
door. All three cargo doors have a balance mechanism which
counterbalance the door weight. A portion of the trailing edge of the
wing to body fairing is attached to the No. 2 cargo door. When the door
is locked, the outboard handle is flush with the exterior of the fairing.
The outboard handle is connected to the door latching mechanism by a
control rod.
I'm unsure as to the exact nature of the doors in Paragrah A, however Boeing does not describe them as plug doors, as I've never flown a 100, Paragraph B applies to me, but is not true of all 200s just some have the 3 door option, all the ones I've flown only have 2.