I have hydraulic dent raiser in 12, 16 and 20 ga like Brownells sell. If you want to borrow one let me know. I have lent them to others before so they could deal with dents. If used properly you can remove any dent and have almost no trace of the repair. Used poorly and I suspect you could regret not reading the instructions or asking for directions. I had a Crescent barrel with a dozen dents in it to learn on.
If you have a metal lathe you can make a set of plugs to do the job. They work quite well if you can make them in several sizes.
