Let's see: Disappointment is caused by expectation, fueled by value or cost as a variable. Sometimes the problem is between the shooters ears.
So what have I bought that I was disappointed in?
S&W Model 63. Cute little snubbie, in 22lr that was as accurate at 7 yards as most shotguns. Check that, it wasn't that good.
Colt Trooper III in 22lr. Shot a thumbnail at 11 yards with a cylinder. Wasn't happy with it, so I traded if for an FA 83, 252. Turns out the chambers are so tight on the 252 seating ammo often took a dowel, and removal likewise.
252 bench rested 1/4" at 50 yards for the new owner. I was expecting the greatest 22lr ever, and, I might have had it, but, it required match grade ammo, or some gunsmithing on the cylinder for standard ammo.
Also, when you buy a 2500 dollar gun, you expect it to have a decent trigger pull, matching the guns potential accuracy, so that would be 1-3 pounds for a 252. It came with a nearly 6 pound trigger. Just what you need on a target grade 22lr, with tight match cylinder. I asked Bob Baker why, and, you'd think I spat on Mother Theresa. Whole thing left me with a bad taste in my mouth.
Walther PPK/S. How did Bond ever stop, or shoot the darn thing with huge hands? Bad trigger, HEAVY.
Mac 11 9mm closed bolt. Not a range gun, heavy trigger, never jammed, but, it really wasn't fun, and wouldn't go full auto, and, in Kali, no suppressor either. Loading 32 rounds of tiny 9mm wasn't fun easy, each time.
Two Browning, FN Hi-Powers. I expected a Browning/1911 type trigger and accuracy. Got neither.