in rash"i d"h rabi yosi he brings a "toysefte" to shlog op the other peshat in the "machlokes" of the mishna
how dose the "toysefte" fit with the hemshech a gemara
(the bigining of the "toysefte" that is) how rash"i explayns rav and shmuel's opinyon in d"h "aval beshar"
yossi stern, NY
Dear Yossi,
Rashi in the Mishnah explains that based on the Tosefta, Hagramah only happens when the knife goes above the upper ring. Going lower is never a problem because all the area of the rings is a good Shechitah area.
Rav and Shmuel argue with R' Yosi b'R' Yehudah that slaughtering through a lower ring is forbidden, even though the lower area is kosher. This is because going through a ring is not called cutting the Kaneh, only between the rings is permitted. (Even staying always inside one lower ring according to Rav is forbidden.) The Tosefta is either according to R' Yosi, or even Rav and Shmuel but then it is only allowing between the rings.
In either case "leaving the ring" in the Mishnah must only mean the upper one, because according to R' Yosi in the area of the other rings you can go up and down and according to Rav if you stay between two rings you're ok and if you're inside a ring it's no good at all.
All the best,
Reuven Weiner