Slight speculation here, but are all of these backwards casing experiences in 9mm? I'm wondering if the 9mm tapered case is somewhat to blame here. Being as the base is narrower than the lips, it would lend itself to fitting in the chamber backwards. 40 and 45 are straight walled cases, so they would have to be a perfect angle to go in, which is less likely.
Slight speculation here, but are all of these backwards casing experiences in 9mm? I'm wondering if the 9mm tapered case is somewhat to blame here. Being as the base is narrower than the lips, it would lend itself to fitting in the chamber backwards. 40 and 45 are straight walled cases, so they would have to be a perfect angle to go in, which is less likely.