Converting old dope with a 100yd zero to a 50yd?

[Phylodog]

I switched from a LPVO and CONV to thermal last year and at the same time switched to a 50yd zero. Unfortunately I don’t have the data written down anywhere, like an idiot I printed it up and stuck it to the side of my rifle. Is there a reasonably simple way to convert it?

 

[Powder_Burns]

ballistics calculator...

JBM - Calculations - Trajectory

www.jbmballistics.com

bookmark it.

 

[Phylodog]

Just start punching in random data?

 

[Powder_Burns]

If you have some guess at to what your mv is roughly, putting that into the solver should give you your correction to 100yd from 50. You may be off by an inch or so, but close enough to get a zero confirmed with 2 shots. Idk if anyone makes an IR boresight, but that would probably get you as close without having to actually trip your sear.
Maybe I’m not understanding your question.

 

[Phylodog]

I think you are, I’m just terrible at math and didn’t know if there was an alternative to trying to guess MV based off of the prior come ups. Thanks for the help