you gotta drill a hole in the guard to use that hole. But it's a spot that often breaks so tighten very gently. Good spot to use a rubber washer or similar.
The mudguard. Drill a hole in it = stress riser so more likely to crack. PDW guards do come with a clip that allows you attach to mounts like that without drilling.
Pretty sure I just used the normal brackets and zip ties on my Inbred where there wasn’t even a threaded hole.
you gotta drill a hole in the guard to use that hole. But it's a spot that often breaks so tighten very gently. Good spot to use a rubber washer or similar.