summon FallingSand ~ ~1 ~ {Block:stone,Time:1,Passengers:[{id:FallingSand,Block:redstone_block,Time:1,Passengers:[{id:FallingSand,Block:activator_rail,Time:1,Passengers:[{id:MinecartCommandBlock,Command:gamerule commandBlockOutput false},{id:MinecartCommandBlock,Command:scoreboard objectives add shot stat.useItem.minecraft.carrot_on_a_stick},{id:MinecartCommandBlock,Command:setblock ~2 ~-3 ~ repeating_command_block 1 replace {auto:1,Command:"/execute @a[score_shot_min=1,score_shot=1] ~ ~ ~ summon ArmorStand ~ ~ ~ {ArmorItems:[{},{},{id:elytra},{}],CustomName:\\\"bullet\\\",Invisible:1b}"}},{id:MinecartCommandBlock,Command:setblock ~2 ~-2 ~ chain_command_block 9 replace {auto:1,Command:"/execute @p[score_shot_min=1] ~ ~ ~ tp @e[type=ArmorStand,name=bullet,r=0] @p[score_shot_min=1]"}},{id:MinecartCommandBlock,Command:setblock ~2 ~-1 ~ chain_command_block 9 replace {auto:1,Command:"/scoreboard players set @a[score_shot_min=1,score_shot=1] shot 0"}},{id:MinecartCommandBlock,Command:setblock ~2 ~ ~ chain_command_block 9 replace {auto:1,Command:"/execute @a ~ ~ ~ execute @e[type=ArmorStand,name=bullet,r=0] ~ ~ ~ tp @e[type=ArmorStand,name=bullet,r=0] ~ ~5 ~"}},{id:MinecartCommandBlock,Command:setblock ~2 ~1 ~ chain_command_block 1 replace {auto:1,Command:"/entitydata @e[type=ArmorStand,name=bullet] {FallFlying:1b}"}},{id:MinecartCommandBlock,Command:setblock ~2 ~2 ~ chain_command_block 1 replace {auto:1,Command:"/scoreboard players set @e[type=ArmorStand,name=bullet] shot 1 {OnGround:1b}"}},{id:MinecartCommandBlock,Command:setblock ~2 ~3 ~ chain_command_block 1 replace {auto:1,Command:"/execute @e[type=ArmorStand,name=bullet] ~ ~ ~ summon FallingSand ~ ~ ~ {TileID:51,Time:1b}"}},{id:MinecartCommandBlock,Command:setblock ~2 ~4 ~ chain_command_block 1 replace {auto:1,Command:"/execute @e[type=ArmorStand,name=bullet,score_shot_min=1] ~ ~ ~ summon Creeper ~ ~ ~ {ExplosionRadius:10b,Ignited:1b,Fuse:0s}"}},{id:MinecartCommandBlock,Command:setblock ~2 ~5 ~ chain_command_block 9 replace {auto:1,Command:"/execute @e[type=Creeper] ~ ~ ~ kill @e[type=ArmorStand,name=bullet,r=1]"}},{id:MinecartCommandBlock,Command:setblock ~3 ~-1 ~ wall_sign 5 replace {Text1:"{\\\"text\\\":\\\"My channel\\\",\\\"color\\\":\\\"dark_blue\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"/tellraw @a [\\\\\\\"\\\\\\\",{\\\\\\\"text\\\\\\\":\\\\\\\"Remember to take a look of my channel: \\\\\\\",\\\\\\\"color\\\\\\\":\\\\\\\"gold\\\\\\\"},{\\\\\\\"text\\\\\\\":\\\\\\\"My channel\\\\\\\",\\\\\\\"color\\\\\\\":\\\\\\\"dark_aqua\\\\\\\",\\\\\\\"clickEvent\\\\\\\":{\\\\\\\"action\\\\\\\":\\\\\\\"open_url\\\\\\\",\\\\\\\"value\\\\\\\":\\\\\\\"https://www.youtube.com/channel/UC3_Gm-pfskCh2bnzcekR0ow\\\\\\\"}}]\\\"}}",Text2:"{\\\"text\\\":\\\"\\\",\\\"color\\\":\\\"aqua\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"/execute @a ~ ~ ~ playsound minecraft:entity.experience_orb.pickup voice @a ~ ~ ~ 12 1 1\\\"}}",Text3:"{\\\"text\\\":\\\"\\\",\\\"color\\\":\\\"dark_blue\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"2\\\"}}",Text4:"{\\\"text\\\":\\\"\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"3\\\"}}"}},{id:MinecartCommandBlock,Command:setblock ~ ~ ~1 command_block 0 replace {Command:fill ~ ~-3 ~-1 ~ ~ ~ air}},{id:MinecartCommandBlock,Command:setblock ~ ~-1 ~1 redstone_block},{id:MinecartCommandBlock,Command:kill @e[type=MinecartCommandBlock,r=1]}]}]}]}

/scoreboard objectives add shot stat.useItem.minecraft.carrot_on_a_stick

Adds a score that increases when right-clicking a carrot on a stick

/execute @a[score_shot_min=1,score_shot=1] ~ ~ ~ summon ArmorStand ~ ~ ~ {ArmorItems:[{},{},{id:elytra},{}],CustomName:"bullet",Invisible:1b}

Executes a player with the score setted at 1 the action to summon an invisible armor stand that is wearing an elytra and is named bullet

/execute @p[score_shot_min=1] ~ ~ ~ tp @e[type=ArmorStand,name=bullet,r=0] @p[score_shot_min=1]

Teleports an armor stand named bullet to a player with the score settled at one. This is used to detect player's rotation.

/scoreboard players set @a[score_shot_min=1,score_shot=1] shot 0

Resets the score of all the players with the score settled at one.

/execute @a ~ ~ ~ execute @e[type=ArmorStand,name=bullet,r=0] ~ ~ ~ tp @e[type=ArmorStand,name=bullet,r=0] ~ ~5 ~

Teleports an armor stand five block up. If you want it to go farther, just increase the number

/entitydata @e[type=ArmorStand,name=bullet] {FallFlying:1b}

Changes the data of all the armor stands called bullet at flying.

/scoreboard players set @e[type=ArmorStand,name=bullet] shot 1 {OnGround:1b}

Sets at one the score of all the "bullets" which are on the ground

/execute @e[type=ArmorStand,name=bullet] ~ ~ ~ summon FallingSand ~ ~ ~ {TileID:51,Time:1b}

Executes all the bullets the action to summon a falling sand with fire id. To know items' id press f3+h

/execute @e[type=ArmorStand,name=bullet,score_shot_min=1] ~ ~ ~ summon Creeper ~ ~ ~ {ExplosionRadius:10b,Ignited:1b,Fuse:0s}

Executes all the "bullets" with the score settled at one the action to summon a creeper that explodes. If you want a bigger/smaller explosion change the "10b" value

/execute @e[type=Creeper] ~ ~ ~ kill @e[type=ArmorStand,name=bullet,r=1]

Executes all the creepers the action to kill all the "bullets in the range of a block"

summon FallingSand ~ ~1 ~ {Block:stone,Time:1,Passengers:[{id:FallingSand,Block:redstone_block,Time:1,Passengers:[{id:FallingSand,Block:activator_rail,Time:1,Passengers:[{id:MinecartCommandBlock,Command:gamerule commandBlockOutput false},{id:MinecartCommandBlock,Command:scoreboard objectives add i dummy},{id:MinecartCommandBlock,Command:setblock ~1 ~-3 ~ repeating_command_block 1 replace {auto:1,Command:"/scoreboard players add @e[type=!Player] i 1"}},{id:MinecartCommandBlock,Command:setblock ~1 ~-2 ~ chain_command_block 1 replace {auto:1,Command:"/entitydata @e[type=!Player,score_i_min=1,score_i=1] {NoGravity:1b}"}},{id:MinecartCommandBlock,Command:setblock ~1 ~-1 ~ chain_command_block 1 replace {auto:1,Command:"/entitydata @e[type=FallingSand] {Time:1b}"}},{id:MinecartCommandBlock,Command:setblock ~2 ~-1 ~ wall_sign 5 replace {Text1:"{\\\"text\\\":\\\"My channel\\\",\\\"color\\\":\\\"dark_blue\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"/tellraw @a [\\\\\\\"\\\\\\\",{\\\\\\\"text\\\\\\\":\\\\\\\"Remember to take a look of my channel: \\\\\\\",\\\\\\\"color\\\\\\\":\\\\\\\"gold\\\\\\\"},{\\\\\\\"text\\\\\\\":\\\\\\\"My channel\\\\\\\",\\\\\\\"color\\\\\\\":\\\\\\\"dark_aqua\\\\\\\",\\\\\\\"clickEvent\\\\\\\":{\\\\\\\"action\\\\\\\":\\\\\\\"open_url\\\\\\\",\\\\\\\"value\\\\\\\":\\\\\\\"https://www.youtube.com/channel/UC3_Gm-pfskCh2bnzcekR0ow\\\\\\\"}}]\\\"}}",Text2:"{\\\"text\\\":\\\"\\\",\\\"color\\\":\\\"aqua\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"/execute @a ~ ~ ~ playsound minecraft:entity.experience_orb.pickup voice @a ~ ~ ~ 12 1 1\\\"}}",Text3:"{\\\"text\\\":\\\"\\\",\\\"color\\\":\\\"dark_blue\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"2\\\"}}",Text4:"{\\\"text\\\":\\\"\\\",\\\"clickEvent\\\":{\\\"action\\\":\\\"run_command\\\",\\\"value\\\":\\\"3\\\"}}"}},{id:MinecartCommandBlock,Command:setblock ~ ~ ~1 command_block 0 replace {Command:fill ~ ~-3 ~-1 ~ ~ ~ air}},{id:MinecartCommandBlock,Command:setblock ~ ~-1 ~1 redstone_block},{id:MinecartCommandBlock,Command:kill @e[type=MinecartCommandBlock,r=1]}]}]}]}

/entitydata @e[type=!Player] {NoGravity:1b,Time:1b}

Changes the data of all the entities to no gravity and 1 of time (to avoid falling sands' destruction)

/scoreboard objectives add i dummy

Adds a score called i

/scoreboard players add @e[type=!Player] i 1

Adds to all the entities' (except for players) score 1

/entitydata @e[type=!Player,score_i_min=1,score_i=1] {NoGravity:1b}

Changes at no gravity the data of all the entities with the score setted at one

/entitydata @e[type=FallingSand] {Time:1b}

Changes the data of all the falling sands to 1 of time, so they don't destroy