Free: Contests & Raffles.
You need to cut out all the meat that's tainted, rinsing won't help those acids soak in quick. Throwing away a whole hind would suck but I wouldn't eat it if it's all tainted, I'd toss anything that has a smell to it if it were me.
Did the quarter in question have bullet damage? If not It should hose off just fine, If the bullet hole & damaged area get all fouled up with stomach contents etc. now you have a way bigger mess. If the bullet goes through the guts then into an off side quarter it's gonna look like you shot it with a 6" hole saw before you get done trimming. Good luck.
The whole quarter should not be wasted. Proper cleaning, trimming and hanging should leave most of the meat not just edible, but of excellent quality.