It's not the muscle that determines strength, it's the CNS and technique. You kinda bring up an area that is misunderstood when it comes to PL'ing and that is the gear. Most people think that you throw on a shirt and you automatically add 200lbs to your 1RM, but this is far from the truth. When describing the role of gear, I akin it to additional layers of connective tissue that is extremely tight. Not sure how much from physics class you recall, but there is something called the normal force that pushes opposite of gravity. When you train in gear you not only have to deal with the weight on the bar, but you have to work with the additional normal force created by the shirt all while trying to stay tight and not let the gear fold you.