If you rent/borrow a rifle, one thing I would suggest is that you discuss in advance on who would be responsible if the rifle is damaged due to no purposeful act on your part. This year, I rented a rifle. The rifle I hunted with belonged to the PH/Outfitter's friend. I was very glad that his friend lent this rifle for use, as I had some issues with the PH's rifle. One day, while I was climbing some hills, a boulder I stepped on let loose and I fell about 15 ft down the hill. I never carry a round in the chamber in a vehicle or while climbing rocky/hilly terrain, so there was no chance of an AD. I got scratched up a bit as did the rifle and scope. It was all cosmetic damage and did not affect the shootability at all (I hunted with it the rest of the hunt). I felt bad as it was his friend's personal rifle and we had discussed rifle rental but no further details on who would be responsible for damages and offered to pay for it. In the end, the PH cleaned it up and gave his friend the rental money and everyone was ok with it. If it was my rifle, I wouldn't have cared for the scratches too much (added character), but felt bad as it belonged to someone else.
Most would assume that if you are paying rental, it should cover accidental damages, but it can get awkward in these unusual circumstances. Best to discuss in advance. This is the first time I rented a rifle. Makes travel a breeze, but there is something to be said about hunting with your own gun.