The Tigers scored just their second goal of the campaign in a 1-1 draw against Cardiff on Saturday, with Curtis Davies' header cancelled out by Peter Whittingham's second-half leveller.
Despite his side's promising performances in recent weeks, Bruce is adamant Hull must be more clinical if they are to remain in the top flight and has called on his strikers to improve their form in front of goal.
"Defensively we’re sound, but we can’t keep relying on the idea that we’re going to keep a clean sheet," Bruce told reporters. "We were relying on that last year, but we saw today, they created one good chance and took it.
"I can’t ask for anything more from the team, the way they’re playing, but our Achilles heel is still there. We’ve gone to Man City and created really good chances. We’ve created chances today. And we’ve got to take them.
"You sound like a broken record. How many times have I stood here and said, 'We should have won by four'? It’s such a frustration, because some of our football at times was good. But I can’t keep saying the same thing."
Striker Danny Graham is yet to find the net in 2013, but team-mate Robbie Brady, scorer of the Tigers' first Premier League goal this season, believes the 28-year-old just needs one goal to get his confidence back.
"He worked very hard and I thought he had a good game," the Irishman added. "The goals will come and once he gets one, they will all flood in.
"He is just due a bit of luck. He’s been brilliant in training since he’s been here and it’s just about putting one in the back of the net now and then others will come."