Ladders!

[Exadi]

I heartily endorse this. So much. Block breakers and turtles work.

Um, what? The only part of that I could see using those for is picking the turrets back up, and neither of those will do that for me.
Anyway, you could recycle the turrets by dropping them through lava held by signs, then water held up by signs, then a drop long enough to kill them. They will drop themselves as an item, then you pick them up with obsidian pipes or something and send them back to the deployer. Thus making this device possible in 100% legit survival.

Be aware that this will gradually convert all your normal turrets to Oracle turrets. Bonus points if you add defective turrets and have them sent on a different path.

 

[KirinDave]

Um, what? The only part of that I could see using those for is picking the turrets back up, and neither of those will do that for me.

Weird because I saw a setup using them doing this. I wonder if they were not the RP2 variety...

 

[Exadi]

I just tried the MFR one. No luck there either. Don't know what the purple frame looking block breaker is... What I tried first with turtles was turtle.dig(). I just tried a melee turtle and that killed the turret but did not pick up the item.