This is essentially what happened to me today.
(SCENE 1: A GUN STORE)
Erin: Hello, I would like to pick up my gun which you have had for a month for repairs.
Owner: Here is your gun. Please pay us.
Erin: I shall.
(SCENE 2: CHATEAU PALETTE)
Erin: Now I shall do a function check of my rifle before I spend money and gas to go to the range only to have the rifle malfunction.
Rifle: (jams in exactly the same manner as before)
Erin: Oh, it is ON, bitches.
(SCENE 3: A GUN STORE)
Erin: Owner, we have a problem, namely, you did not fucking fix my fucking rifle.
Owner: That is indeed odd. Let me see it. (opens chamber, notes that bullet is jammed at a 15 degree angle to the bolt and is completely incapable of being fired)
Owner's Wife: Oh my fucking god, it's still loaded! (goes hysterical)
Erin: (Pointedly ignoring Wife) You will note how it jammed in exactly the same manner as I described, but was unable to replicate for you previously. I left it as such that you might see it firsthand.
Owner: (Also ignoring Wife) Yes, I do indeed see that. How curious.
(technical discussion between ERIN and OWNER dissolves into a series of grunts and clicks which only firearms enthusiasts would understand)
Owner: With your permission I would like to take this to the range myself and shoot many different brands and grain weights of .22 bullets through it to see if I can experience the problem myself.
Me: You do that. (Note: the subtext here is that ERIN has neither the time nor the money to amass a collection of various .22 bullets to see if the problem lies with a certain brand or batch, but that the OWNER clearly does)
Owner's Wife: That gun looks too small for that ammunition, are you sure you're using the right kind?
Erin: (levies an icy stare upon Wife which seems to say, "You clearly know nothing about guns, you idiot, so shut your fool mouth and go back to the register where you belong before you embarrass yourself further.")
Owner: I will take it to the range this very weekend.
Erin: You do that. (see above)
Owner had better hope and pray that Act 1 concludes with Erin happily blazing away at the range, or else Act 2 will begin with Erin lodging said Rifle up Owner's rectum, sideways.