Can a factory Beretta 92 barrel be used in a M96A1??  Just thought if so I could get a 92 9mm barrel and switch back and forth.

The short answer is yes it will work. I have a model 96 that I swap a model 92 barrel back and forth with depending on what I feel like shooting. I'd swap mags with caliber tho.

That's great!  No adverse effects?  The barrels look the same size.

No adverse affects at all. The barrels are the same diameter on the outside. The .40 caliber breech face works fine for the smaller 9mm case. The .40 feed ramp on the 96 frame is bigger than the 9mm size feed ramp on the 92, and works very well with just a barrel swap caliber conversion. A barrel swap conversion going from a 92 frame in 9mm to a .40 cal barrel doesn't always work so well because of the smaller 9mm feed ramp. What you're wanting to do will work just fine. I've been doing it for years with my 96 Centurion.

Yep!

Purchased a new factory 9mm barrel and dropped it into the 96A. Runs flawlessly. Even replaced the plastic guide rod with a new SS guide rod and can change springs as needed.

IIRC beretta used to make a model that came with both slides and barrels.