I once had a Beretta S55BV with duck barrels (Silver Snipe)
I wanted skeet barrels so I sent a letter to Beretta
and gave them the serial number and model and said I wanted
a set of skeet barrels. I asked what I needed to do. They said
send money and an address they already had the specs for my shotgun.
I was in the country of Turkey but rotating home so I sent the money and a stateside address, in a few months here they came
and fit right on. go figure.

This was in 1979.

Mike