Almost any fighter on AH can successfully attack and down a bomber formation with little risk, if one has patience. A lot of people have trouble with bombers because they usually attack from 6 o'clock. That's the result of bombers flying above the usual fighter altitude.
There's two techniques that I read in the BBS and found them really useful, those are the two I've been using most of the time:
1. Get co-alt with the formation, and fly parallel with it until you're slightly past their wingtip and 2-3K away, always flying faster than the bombers (not hard). Turn 90 degrees towards them, get your wings level and shoot. It's easy to hit all three bombers like this, and most gunners don't shoot well when you're making passes from 3 or 9 o'clock. The Tu-2 can't even defend from this as it doesn't have waist guns. Get parallel to the formation again, and repeat.
But my favourite technique is this one.
2. Fly a light Bf-109G14 equipped with rockets. Get co-alt with the bombers, approach from dead six (you don't even need to go fast), place the bombers at the bottom of your sight and salvo your rockets the moment you move from 1,5K to 1K. Enjoy the fireworks. Most of the time you'll get two bombers, or at least one and damage the others. Sometimes I've got all three with a single salvo, you've got a nice chance of this if they are B-24.
A smart buff pilot will defend from 1 by turning and making you face their tail guns, but I've rarely encountered this. When using the second strategy most pilots won't turn or take evasive action, they'll assume you're going to attack from dead 6 with cannon fire. I prefer the Bf-109G14 over the Bf-110 because of the faster climb and because most bomber pilots are careful when they see a 110 attempting this approach. They already assume you're gonna use rockets.