sorry took so long to reply....
its not the guides, otherwise the line would snap before the rig, not in the middle of it. my fish finders are solid plastic. they seem smooth and well made. as for my setup, i use 2 swivels because of casting distance. ive tried using just one swivel but it doesnt cast as far because the bait and weight[fishfinder] seperate in mid air and lose momentum. are there such things as metal fish finders? like aluminum or something similar? i think that would be good for the braided line.