It took a while to get around to it, but here’s “the rest of the story”: I already had a working tool to bend the loop, so I figured that the easiest way to adjust the top part was to make another tool:
I stuck the loop in the tool and tapped it in...
...and then I put it in the vise and pressed it:
I anticipated that the loop would stick in the tool, so I added a hole in the center to be able to tap it out with a punch. It worked like a charm, one firm tap and it came right out:
And here’s the finished product, nice, straight and square:
The greyish one was made from the material GT sent me (thanks again, I owe you one!). It wasn’t really easier to press, it may be softer but the surface isn’t polished so it didn’t slide through the tool as smoothly as the drill rod did. On the other hand, the duller material looks way more authentic than the shiny drill rod, so I think I’m going to ask my buddies in Sweden to look for something similar. It should hopefully be easier to find metric material over there, if not I can always etch the drill rod to make it less shiny.