Mouthpiece Tone Trouble

[holstsuperfan20]

Hi people!

I am a long time forum lurker but I wanted to make an account because I'm experiencing some issues between mouthpieces.
Right now, I am playing on a Wick 4AL, and a Griego Oft base model. On the Wick, my low register is fine, but with less flexibility. On the Oft, I have more flexibility, but notes starting at Bb (bottom of staff) and below sound kind of awful; super sharp, pinched, and airy. I have tried to iron this out for a while now, with little to no results. I was wondering if anyone had any tips or advice, whether its a matter of getting my chops up or another matter. Thank you!

[Nolankberk]

I have a weird marcinkiewicz model based off mic gillettes modified jet tone, and it had those exact same issues. Almost no core to the sound and always played nearly 20c sharp. It's probably just the mouthpiece, but mic didn't seem to have any issues with it..

[Burgerbob]

You're probably tense in the low register and the wick covers it up.

[hornbuilder]

Really difficult to give any worthwhile advice without seeing/hearing you play. How long have you been playing? What sort of level do you play at? How old are you? Do you have a teacher?