Wright's is about the only place you'll get a good quality bolt buffer and it's worth the money as it will last aprox 40000rds. Just about every other company that offers one, offers a product that is made of a brittle material that won't hold up! The best test it to place the replacement buffer on the bench and whack it with a hammer...if it breaks, it was not good enough to go into the gun! Springs are available from many sources...no better, no worse than Wrights. O-rings can be purchased at Napa for a fraction of what a gun shop sells them for. If you're gun is a low to mid serial number and hasn't been used much it will likely still have a blued mag tube. If so, they are prone to corrosion if not cleaned after every outing. The later guns had a chrome plated or stainless mag tube that wasn't as susceptible...but the piston head, sleeve and rings still are. Just clean the gun and corrosion becomes a non issue. Early guns also had the vent-rib held in place with an Allen screw at the tip of the barrel. The screw can loosen and eventually the rib will shear it off as it slides forward under recoil. Best to remove the screw clean it and the hole in the rib/barrel and apply a drop of red locktite before re-assembly. If there's no screw you have the late style soldered rib and don't need to worry about it. Barrels...the 30" full choke field barrels may not cycle light loads very well due to the small gas ports. Those can be drilled out to a larger diameter by a gunsmith. The early guns with "stage 1" trigger (serrated trigger shoe vs smooth on stage 3) have a screw to adjust take up...if you mess with it put a drop of blue locktite on the threads or it can back out and break. The original rebound follower is a poor design. Wright's offers a better replacement, although I've found that you can drill the original a bit deeper and it lasts quite a few thousand rounds more before it fails. Other than that there's not much else to be aware of with these guns...they are the best semi-auto ever built IMHO and today, make the absolute best target shotguns after a little tune up!