kettlebell training

has anyone used a heart rate monitor whilst exercising with kettlebells? If so how many calories have you actually burned?

At an avg of about 75% max HR I burn about 110 calories per minute.

It totally depends on what kind of kettlebell exercises you are doing. Repetitive grinds like presses, get-ups, and deadlifts don't burn many calories if you're using a medium or light weight (relative to your own strength). Even using a heavy weight, you're not likely to burn even 10 calories per minute. That is not to say these aren't important exercises; building muscle is very important for fat loss, not to mention all the other health benefits that come from getting stronger. But while actually exercising, strength lifts don't burn a significant amount of calories.

With ballistics like swings and snatches, however, 10 to 15 calories per minute is realistic, depending on the weight you are using (the heavier, the better, in terms of calorie burn) and assuming a vigorous effort.

FYI, you're going to run into certain members of this site who will try to convince you that HRMs are worthless for kettlebell training because kettlebell swings are an upper body exercise, which is a complete and total lie. It's like saying a squat is an upper body exercise just because you're holding the bar on your shoulders. The kettlebell swing is almost entirely a core and lower body movement. All of the energy is generated from the hips and glutes. If you are doing anything more than just holding the weight with your arm/hand, you're doing it incorrectly, and you are going to hurt yourself.