Sighted in the FF III on a friend of mine's a couple of weeks ago with 3.5 Federal TSS 9x7s and straight 9s. Can't speak to the recoil issue except to say that I was shooting it off a lead sled with 50 lbs of weight on the 15 lb sled. It still jumped, slid back several inches on my shooting bench, and bruised my cheek. No way I would shoot the thing off my 57 y.o. shoulder, but that's just me.
Was not impressed with the factory chokes with the Federal shells. The SF mic'ed .660 and the super spreader .735 IIRC, so very close to cylinder bore. The XF did around 260/10 with both loads which I can easily better with my 2.75", 1&5/8 oz handloads. Shot one through the super spreader, and it blew a 1" hole through my shot trap. Apparently the rear brakes on the stupid flight control wad did not open so the shot was all still contained in the shotcup when it blew through my trap continuing on into low Earth orbit. That's through 7 layers of canvas cloth, a sheet of very expensive stainless steel, and the 3/4" plywood back of the trap...essentially a 2&1/2 oz slug. DO NOT shoot Federal TSS through the supplied spreader choke. I'm sure it would do fine with conventional front opening wads, just not the FCW.
Ammunition issues aside, it appears to be a well made gun as most all Brownings are, although the styling is not for me. Can't help on aftermarket availability of chokes, but I'm sure they are available.