Suggestions, I haven't tried 'em:

Cut a short length of Sched 40 or thicker 3" pipe to go in the opposite
end of the joint. Now the wall thickness is almost doubled, and should
not distort quite so much.

Drill holes into the opposite end of the joint and drive small screws
into them. With those screw heads sticking up, the piece shouldn't
rotate in the chuck.

or....do both of the above.

Best -- Terry