... if my rifle with day time optic will hold 1/2” moa what can I expect with my thermal ?
Nothing special, rem700 SA, criterion 22" medium profile, NF Atacr 4-16 t3, LWTS-LR thermal clipon, fgmm 175gr, RRS tripod with anvil-30 head.
100yds, 8x on day scope, DRT thermal target, day time - I'd never shot a DRT target, and hardly ever shoot in the day time with thermal. You can see the "hood" over the top to shield out the glare. Also, note the LWTS-LR has a grainy image, that's true at all magnifications. It doesn't help with PID, but this thermal's collimation is DOBA.
First 3rd group , at the top, 7/16" (1 bullet when in same hole as another, at the very top)
Second 3rd group, at the right, 9/16"
Avg group size 8/16" = 0.500 IPHY = 0.478 MOA
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Summary, if you can do it with the day scope, you can do it with the thermal. The main issue is wind calls, as you won't have as many visual clues at night.