Phil, there's as many ways to accomplish it as there are guys who do it.
Tell you what, drill the two holes in the guard.
Put a ONE short pin in one of the holes that just barely sticks out of the hole. Press it to the handle and it'll make a little indent. Drill it. Put in a full length pin. Put the short pin in the other guard hole and force them together and it'll make the other indent.
that's not how I do it, but it's easy to explain.
Now, of course, the aggravation and challenge is to have both faces PERFECTLY flat, parallel, the holes PERFECTLY perpendicular, identical depths so the pins are interchangeable, and in line with the handle hole.
You have one thing not right, and you've got gaps.
Those pins are NOT flexible.
As well, your guard shoulders need to be perfect, and on the same plane as everything else, or when you tighten the handle to the guard, and if you've got one item not on the same page as the rest, then you've got gaps on one side of the guard shoulder or the other. Or the top or bottom tweaks one way or the other.
The face of the guard, the back of the guard, the guard shoulders on the knife, BOTH guard shoulders, and the face of the handle material ALL need to be on the same plane and perfectly flat.
If your pins are NOT perpendicular - I mean 180 degrees - to these surfaces, when you tighten things up, you've got a row of gaps.
Phil, by the time you've got the first one done correctly, with no gaps for even light to shine through, you'll have busted all the windows out of your shop, shot the cat, and beat dents in your truck hood with a hammer.