Indeed, may be able to shoot .40 is better. Sorry, when the topic of 10mm comes up I instantly think about Glocks, which I've seen being shot with .40 trouble free.
Aftermarket conversion barrels are a topic most manufacturer's don't like to make people aware of.
I'd say if someone is looking at a 10mm and wants to shoot a lot of factory ammo in it, but not necessarily the most powerful stuff, buying a .40 S&W barrel would be a good idea and pay for itself quickly.
but you didn't originally say you had to buy a conversion barrel. Originally you said you can shoot .40 without and conversion barrel.
10mm is easily converted to .40 S&W, heck it can shoot .40 without any conversion barrel or spring changes, and it's also able to convert to a 9mm. I have yet to see a .45 ACP that can convert to a 9mm and be a reliable shooter.
There's a lot of reasons 10mm is coming back. It has all the strengths of the .45 ACP and more, yet none of the weaknesses.
don't mean to call it out but I don't want anyone thinking they can when they cant...