Is there an app or tool that I can use to see what the trajectory of 855 will be if I zeroed with 193?

No, your zero for the two rounds will not be the same.

I know that hence my question.

I'm not quite clear on your question, but you could use a typical ballistics program and build up drop tables for both rounds if you know the ballistic coefficients of each projectile and their respective velocities out of your particular weapon.

Otherwise, you're just 'wagging'.

Chris

It would be gun dependent. Maybe your gun shoots 855 1" lower than 193 at 100 yards. Unless you know this value then you can't determine any ballistics. Do you know this?

If so then you just need a standard ballistic calculator like AeroE put up.

Edit:

I assumed your question meant that you had your gun zeroed for 193, and wanted to know where it would shoot with 855. Of course you can't know the answer for that unless you KNOW how the impact changes when you shoot 855 at a specific range.

Shooter app

Android or iPhone platforms