tweaking a jailbird

I just received my Jailbird and while the fit is excellent and comfortable, I’m noticing it’s a bit too long when fully flaccid. Even though I used sizing rings and followed MM’s measuring instructions with great care, I feel like trimming about 3/8” off would help. When I manipulate myself with a q-tip, the cage fills up almost to the tip. Does this issue stem from the cage’s curvature, or did my measurements go awry? I’m quite handy around tools, so is there a method for me to shorten the end of the cage on my own? Additionally, the cage section seems to swivel slightly around the post extending from the base ring. Is that typical?

Thanks