I have a Merkel 140A in 500NE and it does the same thing. Part of the problem is that there is a wooden block that the catch mechanism slides against inside the action - seems to be deliberate. I saw this when I had mine pulled apart (will try and dig photos up when I get home). I carefully shaved some timber off it to lessen the resistance and it made a big difference, but it tightened up again over time (I think oil may have swelled the timber).

So, it's not entirely related to a tight lockup but resistance in the lock-up mechanism from another source.