Gemara

40b (Mishnah): If one deposited a barrel with Shimon and designated where it should be kept, and Shimon picked it up for his needs, he is liable if it broke while he was holding it, but not if it broke after he put it down.

If the owner designated where to keep it, whether it broke while Shimon was holding it or after he put it down, he is liable.

(Beraisa - R. Yishmael): If one stole a lamb from a flock or a coin from a wallet, he returns it to where he stole it from;

R. Akiva says, he must inform the owner.

The Reisha of our Mishnah always exempts after he put it down. It is R. Yishmael, who allows returning theft without telling the owner, and all the more so, if he designated a place, for then he returned it to its place!

Question: The Seifa is like R. Akiva, who obligates telling the owner! All the more so, if he did not designate a place, he must inform him, for then we cannot say that he returned it to its place!

Answer #1: R. Yochanan said the Mishnah is not like one Tana.

Answer #2 (Rav Sheshes): Shimon moved it (to use it like a ladder) in order to bring chicks (from a high nest. The entire Mishnah is R. Yishmael. In the Seifa, he did not put it down in the designated place.)

Rav Sheshes holds that Sho'el she'Lo mi'Da'as (one who borrows without permission) is considered a thief. R. Yochanan did not answer this way, for 'put it down' connotes in its place.

41b (Rava): There was no need to mention Shlichus Yad regarding a Shomer Sachar or a Shomer Chinam. A borrower, who uses it with the owner's permission, is liable for Ones. All the more so, a Shomer Chinam or Shomer Sachar, who uses it without permission, is liable for Ones! It was written superfluously to teach that Shlichus Yad does not require Chisaron.

43b (R. Yochanan): The Halachah follows R. Akiva always.

'Always' includes even if he returned it to its place, and it broke later, i.e. the Halachah is unlike R. Yishmael, who does not require telling the owner.

Rishonim

Rif: Presumably, the Halachah follows R. Yochanan, who establishes the Seifa like R. Akiva. We rule like R. Akiva against his colleague R. Yishmael. According to Rav Sheshes, the Stam Mishnah is like R. Yishmael, so the Halachah follows him.

Rosh (3:19): The Rif rules like R. Yochanan.

Rif and Rosh (3:20): We rule like R. Akiva against his colleague R. Yishmael. The Halachah is that Shlichus Yad does not require Chisaron, for Rava says so, and he is Basra.

Rosh: Once he picked up the deposit to be Shole'ach Yad and cause a loss, it is in his Reshus to be liable for Ones.

Rambam (Hilchos Gezeilah 3:11): If one intended to be Shole'ach Yad in a deposit, he is not liable until he did so. Once he was Shole'ach Yad he is liable, even though there he did not diminish it at all, rather, he took it from one place to another in his Reshus in order to be Shole'ach Yad. Shlichus Yad does not require Chisaron.

Poskim

Shulchan Aruch (CM 292:1): A Shomer may not be Shole'ach Yad in a deposit. If he was, even if he did not intend to steal it, just to use it, it is in his Reshus and he is liable for Ones, even though he did not use it yet. Shlichus Yad does not require Chisaron. Rather, if he lifted it for a use that causes a loss, he is liable as if he caused a loss. If he lifted it for a use that causes no loss, he is not liable until he uses it. He is not liable for Shlichus Yad, for he is not Shole'ach Yad since he does not diminish it. Rather, he borrows without permission, which is like a thief.

SMA (3): One who borrows with Da'as of the owner is liable from when he takes it from the owner's Reshus. Tosfos explains that since he intends to use it, it is as if he already used it. Here, it was deposited with him not for usage, so it is in the owner's Reshus until he uses it.

Ketzos ha'Choshen (66:44): The Rashba (952) holds that the oath that one was not Shole'ach Yad applies to documents. What is the reason? In any case he is exempt, for documents cannot be stolen! Perhaps Shlichus Yad is more stringent, because he was a Shomer.

Rema: If he returned it to the place from where he took it, he resumes his law of a Shomer, since he was a mere borrower.

Shulchan Aruch (6): If Reuven deposited a barrel with Shimon, whether or not Reuven designated where it should be kept, and Shimon moved it for his own use and it broke, he is liable, whether it broke before or after he returned it to its place. If he picked it up for its needs, he is exempt, whether it broke while he was holding it or after he placed it elsewhere.

SMA (11 and Drishah 10): The Gemara derived that he is liable for moving it, even if he did not take it from its place.mid'Oraisa. This is why the Rambam and Shulchan Aruch said 'move', and not 'Sholach Yad.' Even though the Tur said 'Sholach Yad', he agrees that he is liable even if he did not intend to cause a loss. If not, he should have distinguished! It seems that he wrote this because the owner was particular not to use it for this, like the Nimukei Yosef said. If the owner were not particular, the Shomer would be exempt after returning it. However, if so, the Tur should have explained this. Rather, the Tur was imprecise. The Rif and Rosh brought Rav Sheshes, even though they rule like R. Yochanan, for Rav Sheshes' law is true (one is liable even without intent to cause a loss). R. Yochanan disagreed only because the Mishnah connotes that he returned it to its place. Ir Shushan says that one is liable only if he intended to cause a loss. This is wrong.

Gra (15): Semag, Hagahos Ashri (1:10) and Hagahos Maimoniyos (Hilchos Geneivah 4:2) rule like R. Yishmael. Rashi (41a DH Ha Shaklinhu) says that we established the Mishnah like R. Yishmael.

Rema: If he moved it for the need of its place he is liable for negligence and exempt for Ones. If the Ones was due to the change of place, if the owner designated a place, he is liable even after he returned it to its place. If the owner did not designate a place, he is exempt after he put it down.

Gra (16): He is exempt for Ones, for Shlichus Yad and even Sho'el she'Lo mi'Da'as is only when he intended to use the deposit itself.

Bach (10 DH v'Im): The Mishnah said 'if he picked it up for its needs, he is exempt.' It did not say 'if he picked it up not for his needs, he is exempt. This teaches that if he picked it up because he needed its place, he has some liability, i.e. for what results from his negligence (of moving it).

Taz: If a place was designated and the Ones was due to the place, the beginning was negligence and the end was Ones. If no place was designated, there was no negligence.

R. Akiva Eiger: If he moved it for the need of its place, he is not Shole'ach Yad because he did not intend to use the deposit itself, but it is negligence.

SMA (13): If the owner designated a place, even if the Shomer put it in a place more secure from thieves and it was stolen, he is liable, for we can say that had he not moved it, the thieves would not have found it If no place was designated whenever he puts it is its place.

Rebuttal (Nesivos ha'Mishpat Bi'urim 7): Even giving to another Shomer is not negligence, all the more so putting it in a better place! If the new place is more prone to a certain damage, e.g. burning, he is liable for any Ones that can be attributed to the new place. Even though a Shomer Chinam is not liable if it was burned, since a place was designated, it is as if the owner stipulated that it be in a place safe from burning.