how can i make transitions to different animations fluid and seamless?

hello i have just learned how to animate guns and objects and i was wondering how i would make an aiming animation transition to a reloading animation smoothly, this could really be asked for any multiple animations but wouldn't switching to a different animation while playing another one reset the characters limbs to the default position and orientation and then start the animation. wouldn't this be very clunky and it wouldn't be very smooth. can some one please tell me how games like phantom forces transition between animations?.