We never had a problem with it in combat. We just pulled them in the aircraft and used the gloves and swapped out the barrels. It is just a click of a switch.
Then again though we hardly ever had to do so because well we used the whole burst method that you are supposed to.....
We never really had the need to fire like that though unless we were landing into an LZ and then it would be put out as much lead as possible until the infantry was out and into some kind of protective posture.