Someone (a horn customer - someone who lives about two hours away) gave me a custom/one-off/never-plated F tuba mouthpiece today.
It was made (years and years ago) by a craftsman known for superb (French) horn and rotary valve building - a very pleasant person with whom I have a cordial relationship on social media. That craftsman gave it to the horn player (to give to me) a year or so ago - a customer who (finally, today) handed it to me.
Being a horn (not tuba) expert, it's a "darn good shot" at being a good F tuba mouthpiece
, and (again) a VERY nice and MEANINGFUL gift. I'm going to put it on display (as a symbol of "friendship with someone I've not yet met in-person"), and I have no intention of selling it. It's a "Hey, I like you, and I'm thinking of you" 
type of thing, particularly since THEY made it. The thing is (per typical with many F tuba mouthpieces...Guess what?) It doesn't play (the dreaded) "low C" particularly well.
I have been crediting the easy "low C" on my so-called "German" F tuba completely to my (yes, remarkably fine) instrument, but nope:
The "easy low C" on my F tuba (after playing this never-met-in-person internet-friend's gift) has a LOT to do with my "Sellmansberger" (again: no "scientific knowledge" here, but a whole bunch of trial-and-error) mouthpiece.
trigger warning:
Mostly, this (again "pretty good") F tuba mouthpiece reminds me of those "popular" makes of F tuba mouthpieces.
again: "good" but just not quite "great" (meaning: not EASY enough to play...too much practicing required - with those mouthpieces - whereby I'd have to constantly remind myself how to "hold my mouth funny" to make those pitches come out properly.
yet another trigger warning:
I guess I see why so many are attracted to the "fluffy" F tubas (whereby - unfortunately - "fluffy" seems to go hand-in-hand with "dubious tuning characteristics"). ie. Those types of F tubas produce "fluffy" low D-flats/Cs/B-naturals (with "fluffy" cloaking "stuffy").
bloke "Buy my mouthpiece(s) or don't. At least, I have them...which is why I designed them in the first place."
