The weapon, when cold, would fire at about 650 rounds per minute (rpm). When it was very hot, after several hundred rounds had been fired, the cyclic rate climbed as high as 1100 rpm. The mechanical functions of the weapon just would not work properly at these high rates. There were several problems that occurred at high RPM, including link separation. A "rate regulator" similar to that used in the M60 Machine Gun was installed in the buttstock. It was basically a shock absorber, (designed by Cadillac Gage Co) that eliminated the recoil bounce off the back plate. This allowed the main drive spring to control the forward velocity of the carrier. With the "rate regulator" installed the cyclic rate of the weapon was limited to about 800 RPM. This resolved the mechanical malfunctions that occurred above 1000 rpm. In combination with the "rate regulator" changes were made to the belt feed system for better reliability.