I had two of them. Please do not take my experience as what to expect, but I sold them to a guy I knew that just wanted to shoot in the yard for fun. He understood the issue; I could not keep them on center.
The bow had good ratings, so I jumped in and found two used ones really cheap, from two different sources. Although they looked brand new, the bows could have been abused before I got them so I will try not to sound too negative. I also am no bow expert. I was shooting Barnett brand recommended bolts in both bows.
The scope mount seemed almost weak to me, even when very tight it still has a good bit of play. After several attempts at sighting the first bow (it was all over the place) I discovered that the scope could be pushed left or right easily. The picatinny rail would rock back and forth. I would look through scope while the bow was on a tripod and could move the cross-hairs 6" left or right (at 20 yards) easily in the movement of the single mounting bolt. I tightened it to the point I thought I would strip it, this almost stopped all of the movement. That problem was fairly well solved, but I still think the scope mount is not what it should be.
Elevation always stayed exactly on, but wind-age was still all over the place, even after tightening the scope mount; as much as 8" to the left or right, or dead on.
I discovered later this may be caused by the limbs being out of adjustment when a friend had a Parker doing the same thing. But I do not know if it is a common Jackal problem.
My second bow was the exact same issue.
Even after thoroughly inspecting, buying a used crossbow is really iffy. Getting it right may cost the same as just buying a new one.
If you get one, get it new, with a warranty. Research out dealers around you that can do warranty work and keep you on center.
"Man is still a hunter, still a simple searcher after meat..." Robert C. Ruark