Tactics are pretty well discussed above. Also, off-angle headons can work pretty well, and are useful in situations where settp diving attacks can't be used (like if the BUFF is very low).
Here's my rundown on the better bomber-killers of AH.
NOTE: For all fighters when doing a dedicated anti-bomber sortie, I recommend a convergence of at least 575 as the sooner you can open fire and score meaningful hits, the better. Also, I like the tougher fighters as they can better withstand the occasional hit from the bomber gunners.
Me-163
Although I don't normally discuss expensive perk planes when recommending a plane to somebody, this one is a special case. If you detect an incomming HQ raid and have little time, this is the plane you need as it will reach 30K in only a couple minutes. Only use it in emergencies though due to the large PP risk.
Bf-109G-10 (30mm + gondolas)
This is THE plane to pick if the bombers are high, and you're not. Long WEP duration, fast climbrate and adequate firepower make this perhaps the best pure interceptor in AH for dealing with high bombers. This plane is difficult to fly though because of controllability issues at high speed so I wouldn't use it unless it was the only plane capable of doing the job (in other words, if you have time to climb pick a different plane unless you happen to like 109's). Fly with one hand on the elevator trim--you'll need it. Not very durable so be extra careful.
FW-190A-8 (4 x 20mm recommended)
This is a decent low to medium altitude bomber killer combining good firepower, ammo load and durability into one package. The high rollrate will also help when doing evasive maneuvers. I choose the 20mm over the 30mm because the ballistics match better, plus the 30mm have a serious performance penalty. 4 x 20mm is enough to kill even B-17's with in short order--aim for their wings.
Typhoon
Good for low to medium altitudes. Great firepower with 4 Hispanos, and good speed too. This is a good choice if you have to attack bombers while avoiding escorts, as the speed will help you stay alive. Tendency to suffer radiator damage means you should pick a different plane if you don't expect enemy fighters to be a problem.
F4U-1C
If you're willing to spend the perks, this plane packs the punch of the Typhoon into a tougher airframe with almost twice the ammo load. This is the best bomber killer available from a carrier (surely that CV is worth the 10 or so perks!). Use that ammo load to "reach out and touch" them, out to 1K or so.
P-47D
Often under-rated since it lacks cannon, the P-47 is still a goodt bomber killer. 8 .50's can get the job done, and the huge ammo load and good accuracy of the .50's lets you open up from greater range (even out to 1K against B-17's). This plane is pretty tough and will survive a few pings--but don't get cocky! The P-47 can be highly effective at ANY altitude, even at 30K plus, something which few other bomber-killing fighters can do.
Yak-9T
The one-hit-wonder, if you can hit something with that 37MM you will kill it. OTOH this plane acts like it's made out of tinsel and blows up if you look at it wrong so "one hit wonder" applies both ways
Definately a low-altitude plane. If you have the altitude, this is the PERFECT plane for the vertical-dive attack.
Bf-110G
Though not often thought of as a buff-killer, the 110G has great firepower (2 20mm and 2 30m) packed into the nose, with a pretty good ammo load to boot! Slow climbrate means this one is best for use at lower altitudes.
Mosquito
If you can avoid getting hit, the Mossie will shred anything quite well. 4 hispanos, with good ammo load, all packed into the nose pack a heck of a punch. This plane is a pretty large target itself though so it's best to work with a wingman who distracts the gunner while you move in for the kill. Like the 110, poor climbrate limits its usefulness to lower altitudes.
N1K2
Good firepower, good ammo load, good climbing and diving ability, decent durability, and great maneuverability make this plane a natural bomber hunter although it's seldom used as such. Thanks to the ammo load, your effective range against bombers is about 900 yards (1.1k or so on a headon) so getting kills is easier. In addition, the N1K can furball all day long so it's the natural choice if you want to be able to kill bombers AND dogfight. It's a bit slow though so don't try to chase down bombers with it--only attack if you can get into position beforehand. Performance drops off above 18K.
Of course, any fighter (and some light bombers) can be used to intercept Buffs, but not all are equally good at the task. The above planes are what I feel are the best readily-available interceptors currently available in AH.
J_A_B
