Just wondering if I could ask a question of how likely the following is to be a problem with barrel alignment.

I was in my garden today, big garden, 2 dozen metres maybe, and I had a slab of wood that used to be part of the old kitchen. I was shooting at markers and occasionally some bullseye sheets I had been given and one thing seems to happen that I just can't seem to fix.



Target is here ______________> (X)
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04cm?
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Pellet lands here ________________________> (X)
12cm off to right of sights



Now don't get me wrong I'm not a bad shot and without blowing my own trumpet here I think I'm a pretty good shot and I seem to have managed breathing control for longer shots that yes, its an empty field with nobody in it, I take the occasional shot at some metal sheet somewhere.

But I'm basically wondering, no matter where I aim and how much I adjust the sights, even with the "scope" that came with it, which doesn't seem to work either when I adjust it, is the barrel bent maybe? The rifle itself is second hand, though looks like its been dropped. SMK XS36 2UL/Underlever.
If it probably is I'll see about repairs from somebody.

What makes me think this is that no matter how many hours I've wasted adjusting sights, the sights can even be adjusted maximum amount up or down or right/left and there's only like 1-2 cm difference before many of the measurements appear to be seemingly useless.

I don't know, I'm very sure though that that isn't error on my part because I've spent about 5 hours over a few days just dealing with it, getting mad and trying to adjust for an hour or two again then dealing with it and finally giving up.
I guess it may even be possible that the sights are damaged/off a good bit.