dry and live

14:59 Jul 8, 2014 

I agree with orgogozo, dry firing isn't tir à blanc, that's blank firing.

To blank fire an automatic or semi-automatic weapon it needs to be modified temporarily or permenantly in the great majority of cases.
I would imagine that the exercises are carried out with the unloaded weapons (dry firing) up to a certain standard before issuing ammunition and carrying them out as a live firing exercise.

If it were blank firing first followed by live firing it would require having 2 sets of weapons or modifing them between times.

Blank firing is not without risk as particles leave the barrel of the weapons when fired so you can allow more mistakes to be made when dry firing

14:30 Jul 8, 2014 

tir à vide et tir réel