It isn't because of cleaning. It is because of less wear and less lube needed to run them. This is why "this method virtually eliminates malfunctions common to direct impingement gas systems since hot carbon fouling and waste gases do not enter the receiver area. The rifle stays cleaner, reducing heat transfer to the bolt and bolt carrier, and drastically reducing wear and tear on other critical components. The service life of all parts is increased substantially"
That is from their brochure. I have fired the 416, ran 3-30 rounders through it and was handed the bolt. It was not hot nor even remotely warm. When they ran over 20,000 rounds (full auto in one weekend) through a 416 without a hiccup. It still was shooting well within military accuracy specs... The life span of the rifle is 3-4 times the standard M4. They are more forgiving in sand water and dirt. That is why the Navy seals use them. That is why the marines are replacing part of the M249's with them...
" The strongest reason for the people to retain the right to
keep and bear arms is, as a last resort, to protect
themselves against tyranny in Government...." - Thomas Jefferson