The Light Blues made their intentions clear from the first whistle as John Fleck picked up the centre pass and ran straight through the Buddies only to shoot narrowly wide within the first 10 seconds.
The Hosts were determined to put up a fight and Gallacher had to be on his toes soon after to turn a powerful shot from Jon McShane round for a corner.
The breakthrough for Rangers came in the 7th minutes as the St. Mirren defence failed to clear their lines when Faulds tackled McShea in the box, just as the winger lined up to shoot, the ball broke to Steven Gaffney who then inexplicably passed straight to Isa Bagci, the big Swede then strolled past two stunned defenders before rounding Darren Stewart and slotting the ball into the empty net.
Craig McShea was given a rare starting place and the little winger made the most of his opportunity to show what he could do, unluckily shooting wide after a great run through the middle.
However, McShea made amends for his miss when he began the move which led to the Champions second on 14 minutes.
Fleck picked up the pass from McShea before rounding the exposed Stewart but the Saints keeper made a good block to deny the diminutive striker only for the ball to break to the on running Efrem, the Cypriot making no mistake as he blasted the ball high into the roof of the net.
Although rooted to the bottom of the table the Paisley side were still showing plenty of commitment in a match which was being punctuated by a constant stream of free kicks awarded for niggling trips and fouls.
It was from one such free kick that Gallacher showed why he is the No. 1 choice for the Under 19's as he fingertipped Chris McMenamin's goalbound effort over the bar.
As the match entered the 29th minute John Fleck found himself 35 yards out from the home goal line, moving forward and with passing options limited he brilliantly sent a chipped shot over the head of Stewart and into the top corner of the net to put the league leaders three up and in easy street.
Just before the break Fleck was involved again when he set up Bagci, only this time the big striker's shot went agonisingly over.
Half Time - Saint Mirren 0 Rangers 3
The second half followed the same pattern as the first with Rangers going straight for the jugular from kick off, this time Efrem setting up McShea who shot across the face of goal.
Fleck had another chance when faced 1 on 1 with Stewart, but on this occasion the glory went to the keeper.
The match was still being plagued by the high number of infringements, making a free flowing spectacle for the 50 strong crowd impossible, although some would commend referee Jim McNeil for keeping his cards in his pocket, however the Buddies Andy Stirling was shown yellow but that was for some back chat.
It took until the 70th minute before the Light Blues scored again and it was another defensive calamity when a slack pass went straight to Isa Bagci, who by now must have though his Christmas was coming early, and once again rounded Stewart to finish with an easy tap in into the empty net.
The visitors then went nap in the last minute of the match when Steven Stirling played in substitute Jeroen Van Den Broeck whose perfect cross to the far post was met powerfully by Danny Wilson as he rose above everyone else to bullet the ball home and finish another good day at the office.
The Teams;
Rangers - Gallacher, Perry, Kinniburgh, Wilson, Harvey, Stirling, McShea (Craig 75), Kindbendiksen, Bagci (Van Den Broeck 81), Fleck (Little 75), Efrem.
Subs not used - Vaiculis, Donald, Campbell, Forbes.
St. Mirren - Stewart, Rawcliffe, Love, Gaffney, McMechan, Faulds, Carson (Devlin 54), McMenamin (Burns 70), Quinn, McShane, Stirling.
Subs not used - Cunningham, Quirk, Gair, Crighton, McCabe
Referee - Jim McNeil
© Iain McKee, 24th November 2007