I'm a bit reluctant to bring this up, for perhaps obvious reasons.
I own a Umarex Octane, and I am very sorry I bought the rifle. Barrel droop in one of several reasons. I "think" I have solved the screw-loose issues, along with the necessity of retightening the barrel cross bolt. But even then, every time I dig it out of the closet, it shoots a bit lower than the last time. I've gotten to the point that I turn the vertical scope adjustment about 4 to 6 clicks before I even cock it!
Over time, I've measured the straightness of the barrel using a short straight edge. I haven't noticed any deviation, until last Saturday. I'm guessing, but it appear that laying the straight edge on the back of the barrel, there is about a thousandth of an inch between the muzzle end, and the straight edge. To me, at least, this makes some sense. The reason is, the vertical displacement has always been worse than the horizontal displacement. Assuming that is true, it is easy to assume that barrel bending (drooping by any other name), is a fact of life.
The Octane requires almost more force to cock, than my 75 year old arms are capable of accomplishing. It is infact, heavy enough that the muzzle break loosened up its apparent epoxy sealant (I can now rotate it).
I'm not saying that all break barrel pellet rifles are bad. And, I'm not saying the Umarex is worse than others about barrel bending. But gosh, guys, when the barrel is metal, and the cocking force is 40 to 60 pounds, isn't it reasonable to assume, that barrel bending can, and perhaps is, an issue?