A bit of a story to help illustrate... I bought a Danishreturn a dozen years back and attempted to sight it in. It shot right of POA at 25 and when adjusted, the error was back at 100. When adjusted, the error returned at 200. Now go back to 25 and you shoot far to the other side. I thought the sights were out of index and went home to index the barrel. When I cam back, the same thing happened but started at a lower point. I was up to the range and home four times that day. Turned out the barrel was bent, way back where it's thickest. That didn't happen anywhere along the way, the barrel was brand new and a 1960 VAR issue. Every time the gun went out to be zeroed it was wrong so back it went and reissue a new one. That's the easiest thing to do. I had to remove it and use a hydraulic press and make a straightness gauge to sort it out. About six inches forward of the breech, the gauge wouldn't pass...that was from the factory.
When they finish the barrels they go to the heat treating ovens and they droop after heating. They have to be straightened by men paid to do that very thing. All of them...except this one. Brand new in 1960 and never right.