Building this MOC is challenging, as it a bit top-heavy, it has some stability issues, until it is finished and really doesn't like resting on its sides in the second half of building it. I mitigated that, by building a stand from bricks i had, to keep it from falling over, and that stand is now kept for safe display of the rifle.
The quality of the bricks was good, but i was missing at least one of the needed rubber bands (at least 4 needed, only 3 provided), but that was a minor issue.
When finished, the rifoe is reasonable stable, and doesn't lose parts, if you don't force it. The MOC can be handled well with two hands, but i wouldn't hold it just by the grip (that is by design, not brick quality). It looks great and is cool for some photos and as a display model.
I would not recommend it as a first MOC-build, as there some advanced and delicate techniques, but it is a very rewarding build, that has some inspirational elements, that i liked a lot.