main squeeze form cleveland

hi guys i have guestion about setting rivets with main squeeze ,when im trying set rivet the opening between rivet sets seems to be little bit less then real rivet lenght after setiing ,what it does when im setting rivet ,basicly the handles trying open them self any idea what im doing wrong thanks

No problem. Same thing with any other (normal) squeezer, including a pneumatic setup. The yoke flexes a bit when force is applied.