Learn the snap shot: short wind-up, pressure into the ice, wrist snap, a quick release with more power than the wrist shot. A progression with milestones.
The snap shot is a shot with a short wind-up: you put the blade into the ice just behind the puck, load the shaft with pressure and snap the wrists through. It is released faster than the slap shot and is harder than the wrist shot. Hockey Canada counts it among the seven basic shots that every player should master [1].
The honest answer to "how hard does it go?": right between the two. A long wind-up as in the slap shot brings more speed but costs time; the wrist shot is quickest to release but less hard. The snap shot is the compromise players choose in traffic and on the move. Hockey Canada says: the speed of execution is as important as the speed of the puck, and the element of surprise is an important factor [2].
Technique alone is not enough, but it is trainable. In a study of 16 adolescents, twelve weeks of training with light (60 g) and heavy (260 g) pucks increased shot speed in the snap shot by 7.4 to 8.5 percent and in the wrist shot by 13 percent, and accuracy by 14 percent [3]. The study design was simple (light first, then heavy), so this is a hint, not proof.
Prerequisites you can check yourself (practical standard, not a study):
Hips toward the net, hands slightly further apart than in the wrist shot, the puck beside the foot on the shooting side ("inside foot") [4]. Milestone: you stand stably in this position for 10 seconds without the puck wobbling.
Pull or push the puck toward your feet; that changes the release angle and surprises the goalie [4]. Milestone: you manage 5 pucks in a row that lie calmly on the blade in this position.
The blade goes back only a short distance, no further than roughly hip height. No swing as in the slap shot. Milestone: your partner sees hardly any preparation before the puck is gone.
Put the blade into the ice a few centimeters behind the puck and press down until the shaft bends — in the slap shot the shaft bends much more than in the wrist shot [5]. In the snap shot this happens to a smaller degree. Milestone: you feel the shaft give.
Snap the wrists through so the puck shoots forward. You can shift the weight from the back to the front leg, which brings more body into the shot, or shoot off one leg — that is quicker [4]. Milestone: 8 out of 10 pucks go flat on goal.
End the shot in a stable position, eyes on the puck, blade to the net [4]. If you turn back too early you lose power and position. Milestone: 6 out of 10 hit the chosen corner from 6 meters. After that from slow skating.
The snap shot also reaches high puck speeds. Shoot only at the net, never toward people, and watch for teammates behind and beside you. Goalies need full equipment. Wear a helmet with face protection: in an NHL analysis, visors reduced eye and other head injuries but not the number of concussions [6]. Warm up shoulders, wrists and trunk. This guide explains and motivates; it does not replace supervised training.
Use the foot variant for surprise. A puck that you pull or push toward your feet can be snapped straight off the foot without bringing it forward [4]. That shortens the path to the release. Alternate between wrist shot and snap shot so the goalie does not know which one is coming [4]. More on shot power: in a study of 40 people, skill and body strength determined puck speed — hardly the stick construction [5].
A snap shot is a shot with a short wind-up in which you press the blade into the ice just behind the puck and snap the wrists through. It is released faster than a slap shot and is harder than a wrist shot [1][2].
The wrist shot has hardly any wind-up and the quickest release; the slap shot has a long wind-up and much more speed [5]. The snap shot lies in between: short wind-up, pressure into the ice, wrist snap.
With technique and strength: load the shaft, use your weight, snap the wrists through. In a youth study, heavy pucks in training helped raise speed by around 7 to 8 percent [3]. Stay at moderate weight and clean technique.
The wrist shot first, because the snap shot builds on stance, puck handling and wrist use. Hockey Canada leads shooting practice from stationary shots to shots in motion [1]. When the wrist shot is in place, the snap shot follows.
The Slap Shot in Ice Hockey: Technique, Stick Flex and Progression