Firstly, they would have to capture two.

Secondly: that would take them some time, and that for following reasons.

Firstly, they would have to capture two. So far, there's no evidence they've captured even half of one.

Secondly: that would take them some time, and that for following reasons.

What's crucial about effectiveness of NATO's 155mm howitzers are two things:

- shells designed by Gerald Bull, and

- higher efficiency of explosives they pack (in comparison to the Russian shells of 152mm, NATO 155mm shells are creating about 40% more overpressure).

Obviously, nothing of this would be all too much of a problem IF Russia under Putin wouldn't be organised the way it is: that is, as a system where Putin is a 'shareholder' in every enteprise and extracting his cut, first and foremost. In that system, there is simply no way for something like 'reverse engineering', or 'high tech' - because invesetment into new technologies is very expensive and would instantly make any such effort unprofitable.

That's, BTW, the bare essence of why such projects like Su-57 are failing, too.