Best gun to use against The Twins/Skeletron Prime/Plantera?

[Acacia]

Title says it all, im having trouble with those 2 mechanical bosses and I'd like to know a good gun for Plantera as well.

[Acacia]

or bow, just a ranged weapon

[Distruebix]

Since You didn't list the destroying Im assuming you defeated him. The best weapon avaiable right now is the Megashark (IMO) Use crystal or Explosive bullets

[Mega Munchy]

The best choices of guns you can use are the Clockwork Assault Rifle, UZI, or Megashark with crystal bullets.

[jiink]

Megashark with crystal bullets, Reforged Hallowed or adamantite Repeater, Shadowflame bow, and Stormbow with holy arrows.

[DestiniesEnd]

Skeletron Prime I have great luck using the Daedelus stormbow combined with a set of wings. Basically end up flying oval patterns around him. Slowing my descent on the way down to keep him just on screen so the arrows will continue hitting him. Make a run by my timer activated heart statues at the bottom if I need it. I don't even bother with anything but wooden arrows. Just keep your aim in his general direction and you should shred through his arms. Once he loses a couple the fight becomes much easier.

Haven't even fought him in range bonused armor yet. Almbushed me in spider armor with a summoner build I was messing around with. I'm looking forward to trying the frost armor set with it.

Haven't beaten the twins on expert yet since they keep ambushing me when I'm not really set up for it. Though on normal I did it with a similar set up. I focused on killing Retinazer first before moving on to Spazmatism.

Plantera I can't offer any useful advice. I haven't tryied fighting him with the proper preperations yet. Trying to fight in the naturally created underground jungle caves I have learned is a bad idea. But by that point you can get the Chlorophyte shotbow.

[Fumo Bnnuy n Frends]

usually i could craft the terra blade by then
but if i were to choose i would say go for the mega shark / daeldeus bow w/ holy arrows
skeletron prime and the destroyer use the bows since theres alot of segments on the destroyer
skeletron prime has multiple segments that hover too so the bow benefits alot
for the twins use either ichor cursed flames or crystal bullets
in all 3 nimbus rod is a must asyou can summon 2 and stay in one area while they take damage from the clouds as well

[Acacia]

a resounding suggestion for megashark with crystal bullets, I'll get right on that. Thanks guys!