Im currently playing RE5 on professional with a friend, but right now we're stuck at the boss fight with Jill. At our best run we "attempted to rip the thing off her chest" 28 times, but did not successfully rip it off. We even tried to shoot the damn thing 2-3 times with a magnum (if that makes any difference) before starting to rip it off. I've seen videos on youtube where people manage to do it in 13 attempts, if they aren't fake?, since we couldn't do it in 28 attempts.
 
But does anyone have any advice on how to beat this boss on professional?

If ur stuck there, just keep doin what ur doin and after awhile you'll rip it of her chest. I remeber it took me a long fuckin time too.

Shooting it seems to work best, I'd recommend using the first pistol for that, after several tries of doing that try ripping it off a few times, that should do the trick

Dude, you just spoiled some of the story for me. It's not that Resident Evil 5's story is actually worth caring about, but you could've at least put a "Stuck at... *SPOILERS*."

Yeah, it takes forever. I also recommend shooting the thing with the L. Hawk but you'd better be a sharpshooter because if you miss, it is literally game over.

" @FlamingHobo: Yeah you're right sorry. It didn't cross my mind since RE5 have been out for over half a year. I'll try and get it fixed. "

I remember this fight, ha. I tried to get the achievement while playing it on the hardest difficulty. It took FOREVER.