Here's two solutions that work for me.
01 - Wilcox RAPTAR on top of NF 7-35x T3 behind BAE UTC-x thermal clipon
02 - SilencerCo Radius mounted on Trijicon Patrol
Both of these offer range finders which work in conjunction with thermals.
In case 01, I use NV devices to zero the RAPTAR aiming laser to the center of the day scope reticle at a man made object at 415 yds distance ... and then when I mount the thermal clipon in front of the day scope, I can range anything that I point the center of the day scope reticle at. I'm zeroed at 100yds, so I can only range when my elevation dial is set at 100yds. But I'm using a T3 "no dial" reticle, so I hold for both wind and elevation for every shot.
In case 02, I use NV device on a second gun to help me zero the aiming laser of the Radius to the same point on the object at 415yds that the center of the patrol reticle is aimed at. I used an RRS tripod for aiming the Patrol and a manfrotto tripod for the NV observing gun.
This results in giving me a handheld range finder.
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Do you need a range finder ? As Plinkit says, depends on the distances you are shooting and the cartridges you are shooting.
If the "danger space" (in the Applied Ballistics sense of the words) of your rifle/cartridge combination is less than half of the size of the vertical kill space on your target at the farthest distance you are shooting AND you can accurately estimate whether the target is inside that distance without a range finder, then no, you do not need a range finder. Otherwise a range finder will help.
