I've owned a S&W Super 9 with the 9mm accurized barrel for over a year and have put 1,000 rounds through it without any trouble. Mine is a single action with a wide trigger and a 5 inch barrel. It's more accurate than I am, but that is usually the case with most pistols. I can't comment on the extra barrels, but mine cost about $800 NIB. The only touble I've had were the mag springs had to be replaced on some 15 round MecGar magazines since they would lock the slide back with one round left in the mag. CDNN Investments has a good selection of 5906 hi caps priced right. Enjoy!