Mouthpiece receiver question

[Big Toot]

So, the tuba I am currently using, an older Amati 221 BBb, has had its mouthpiece receiver changed out at some point in the past to a much smaller bore (It's around 10 mm diameter). I am seriously considering having it changed back to what the 221s currently sport, but I was wondering: what differences will it make in my sound? Will it change intonation? I've searched around on the Internet and I can't seem to find a good answer.
Thanks in advance.

[Big Toot]

Fascinating. The receiver that is currently on my tuba is not, however, original to that tuba. If I change it out for an actual tuba standard shank receiver, what, if any, difference will this make?

[Big Toot]

I don't want to reverse it if there's no reason to. If it would change the intonation of the horn, that might be something I'd consider doing it for, which is why I asked.

[Donn]

what differences will it make in my sound? Will it change intonation? I've searched around on the Internet and I can't seem to find a good answer.

If a mouthpipe tube's small-end INSIDE bore is 1/2" or smaller, I probably would view the "bass trombone shank" receiver size as appropriate.

If a mouthpipe tube is larger than this at the small end, I would probably view a "tuba standard shank" receiver as appropriate.

If I change it out for an actual tuba standard shank receiver, what, if any, difference will this make?

How big is the mouthpipe tube's small end inside bore?

[Big Toot]

Since I don't have calipers, the receiver seems to be 18.5 mm in diameter.