the fit and balance is much more important. my favorite shooter is 3" 20br b.c. miroku o/u ejector with 28" barrels. at close to 6.5lb it's hardly a bantamweight.
my lightest 12br was remington 31L with 30" tube. it's weight was ridiculous 5&3/4lbs. it's been replaced by 6.5lb winchester model 12 sixteen bore.
i also use berkley digital tournament fishing scale.