We need a new category... Blunders and miscues?

[Smoke4320]

couple years ago had a customer bring me a Chippa 22 Beretta M9 copy .. Said it would slam fire

did the normal things .. made sure the firing pin was clean clear and functioning properly ..
for the next 4 days several, times each day, I would load a mag go outside and cycle the action
cock, drop the side, eject the rd, recock slide and repeat thru the whole mag
not once did it slam fire ..
just before calling the customer to pick up I loaded one rd in the mag . Did not go outside .. standing by the phone on the counter I dropped the slide and shot the credit card machine
now keep in mind at this point I had cycled at least 100 rds thru the gun without a single slam fire
taught me a lesion I hope to never repeat

[Hickok]

Smoke, I bet the Mrs. was proud of you!

[Ballistics in Scotland]

One round? If the slide contacts and presses down the round after the one it is chambering, it may soften its forward movement. Next step, if you think it rates a next step, would be to remove or tie back the hammer, and see if it slamfires due to poor control of the firing-pin's inertia.