Beowulf,
You asked "Has anyone here actually had success bending a rifled barrel?" Yes, I have. I had the exact problem you describe with a 38" B-weight in .50 caliber and was able to "bend her straight". But first......
I agree with the above posts, first make darn sure the barrel actually is bent and not some other problem. On mine the muzzle and breech holes were centered, the fired patches looked fine and I was getting 1 hole groups at 25 yards, only about 6 inches left of point of aim. Moving the sights as far as the dovetails would allow did help but the sights looked like they were about to fall out of the dovetails.
I took the barrel out and laid a 4' straight-edge along each barrel flat and measured the widest gap with a set of dial calipers. I marked the spot on each flat and noted the measurement. The gap on the left flat was .120" and on the right flat it was .040".
At this point, I called the barrel maker to discuss the situation. He outlined the measuring process (which was just the way I had done it), so I told him my findings. He agreed it was bent. He is convinced UPS uses his barrels for prybars sometimes. He told me to try bending it and if it didn't work, he would replace it.
You are right about these barrels being springy. You have to bend them way past where you want them to end up. Figure out which way you want to bend it, jig it up on blocks at each end and apply force. I used a big c-clamp with a dial indicator to guide me. Bend a little, measure the gap. Bend a little more, measure again. Nothing. Bend a lot more. Measure again. Nerve wracking, but I finally got her done. Shoots like it's supposed to now. Good luck.
-Ron