How many rockets do you need to destroy Metal window bars in Rust?

[Terence McCormick]

Need to know this ASAP

 

[Wikkedly]

The metal bars cannot be destroyed directly (currently). Only the window it is attached to can be destroyed and they do not strengthen the window. Do not place Explosive Charges on these bars as they will be wasted. Place them on the actual window.

I'm not sure about rockets but i know that c4 takes 3 - 4 charges