Tim Cronk returned a blocked punt for a touchdown, while Rolly Lumbala also had a one-yard rushing score for the Lions (5-6). Paul McCallum added a field goal and a single.
Henry Burris threw a touchdown pass to Larry Taylor for the Stamps (7-4) and backup quarterback Drew Tate added a late rushing TD. Rene Paredes kicked a pair of field goals for Calgary, which fell to 2-4 at home.
With B.C. leading 11-6 at halftime, Lulay tossed a 48-yard touchdown pass to Foster early in the third quarter after he got past Calgary cornerback Geoff Tisdale.
Burris then responded right back and engineered a five-play, 70-yard drive that culminated with a 15-yard touchdown pass to Taylor to make it 18-13.
But Calgary couldn't build on that momentum, even after rookie Anthony Parker intercepted an errant pass by McCallum on a failed trick play by the Lions.
Instead, Paris Jackson blocked a punt by Burke Dales and Cronk promptly picked up the ball and rumbled into the end zone to put the Lions up 25-13 after three quarters.
The Lions added to their lead in the fourth when Bruce hauled in a pass from Lulay for a 41-yard touchdown.
With Burris out of the contest after completing 15-of-20 passes for 184 yards, Tate led the Stamps on a four-play, 101-yard drive and capped it off with a one-yard rushing touchdown to round out the scoring.
On Calgary's first play of the game, Burris tossed a pass intended for Romby Bryant that was picked off by Dante Marsh. After the B.C. offence went two-and-out, the Lions had to settle for a 56-yard punt single by McCallum.
The Stamps answered back with a 17-yard field goal by Paredes to take a 3-1 lead after the first quarter.
The Lions went up 8-3 after a one-yard plunge by Lumbala to cap off an eight-play, 56-yard drive.
McCallum then booted an impressive 48-yard field goal before Paredes responded with one of his own from 41 yards out with nine seconds left in the first half.
Notes: B.C.'s streak of not allowing an offensive touchdown ended in the third quarter when Taylor scored for Calgary. The Lions had not allowed an offensive touchdown for 15 quarters over a span of 235 minutes 26 seconds. ... McCallum has made 22 field goals in a row. His last miss was from 57 yards out back in the second week of the season. ... Burris now has 40,642 all-time passing yards to move past Tracy Ham and into seventh spot all-time among CFL quarterbacks.