I believe I have read that before. I think it is standard procedure for most action films with heavy guns. Just imagine how hard it will be to concentrate on saying your lines if you had very heavy guns strapped to you and in your hands.
I was actually curious if any of the matrix guns had been real. Do you know for a fact that the guns they fired were real? I'm simply asking this as a video producer. If there's anything I learned about creating gun scenes, it is that plastic guns are easy to make look real (I.e. have them shoot CG bullets or muzzle flares). I figured that movies like the Matrix either used that technique or did a similar thing with real guns and blanks. Does anyone know which technique they used?
There is a guy that goes into serious depth with this: Source 1 and even tells you if they were holding the guns properly and why he would or wouldn't use the guns in real life.