You think a bodybuilder has muscle size similar to a gorilla?
BZZT! WRONG!
Gorillas have enormous muscles. The leverage of the attachments is different, and the psychology of 'too heavy' is non-existent as they have no reason to engage in such abstract thinking.
BTW, for those wondering just how strong a gorilla really is, there are some accounts that give us some insight. I have personally seen a gorilla snap a bike tire with its hands. It was at the San Diego zoo years ago. The gorilla was playing, it seemed, but was also agitated for some unknown reason. It flexed the tire several times before stretching it to the point of breakage. Incidentally, it looked easy.
There is a fairly in depth account of a female chimpanzee executing a one handed pull of 1200 pounds, but I forget where this reference is. A chimp, folks. Not a gorilla.
Gorillas are unbelievably strong. MUCH stronger than the strongest men...by a HUGE factor. In the book "Raw Power, Building Strength and Muscle" (title may be off a touch) it is asserted that a gorilla's strength would allow for a 4000lb bench press.
That's natural strength, without training or steroids! This is equivalent to a bench press of roughly 10X their weight. Also, it is commonly noted that gorilla's chests are as wide as five feet. Keep in mind that is the average height of a gorilla as well, so they tend to be very nearly as wide as they are tall.