Yes, they are already very susceptible to damage. The damaged guns won't be obvious because the bomber may only be firing one gun, but on your end it appears that all guns are firing at you.
I like hunting and attacking buffs as much as I do flying them. Stay fast (+400mph), make slashing on the buffs making diagonal attacks from at leat 3k feet above them. Once you make a run, convert your excess speed back into altitude and reset your attack fromthe opposite side. This takes practice and patience, but it's the best way to survive. Some buff pilots are very good gunners or just get lucky in some instances, but don't get discouraged.
