TromboneChat

My current small shank mouthpiece is a King M21. Most of the plating on the rim is worn off, so I'm looking into buying a new mouthpiece with a similar size/shape. Any recommendations?

There are a number of small-shank mouthpieces sort of similar to a King M21
(24.40mm cup I.D., 5.85mm throat, rounded rim). You might try:
• Bach 15C
• Bach 12C (readily available used) - or its many clones, from Faxx, Conn, Blessing, Jupiter, ...
• King 11M (flatter rim than M21)
• Schilke 45
• Yamaha 45C2-12C

You may also find a used King M21 from a TromboneChat member.

Posaunus wrote: ↑Mon May 28, 2018 4:36 pm There are a number of small-shank mouthpieces sort of similar to a King M21
(24.40mm cup I.D., 5.85mm throat, rounded rim). You might try:
• Bach 15C
• Bach 12C (readily available used) - or its many clones, from Faxx, Conn, Blessing, Jupiter, ...
• King 11M (flatter rim than M21)
• Schilke 45
• Yamaha 45C2-12C

You may also find a used King M21 from a TromboneChat member.

These dimensions are correct if the OPs mouthpiece is the M21 with the groove knurling around the rim of the mouthpiece. However there was another, older version of the M21 with a coin Knurling around the rim, which is the same version that JJ Johnson played. The rim size on these versions were closer to a 7C sized piece.

Additionally, the M21 has a drastically different cup shape and depth than most of these smaller pieces. They are deeper and more conical, compared to a 12C or 15C.

The King 11M is a good recommendation. Denis Wick might also be a good place to start as well, like a 10CS or 7CS.

Or, you might just want to look for another M21, as also suggested above. They are out there and they pop up from time to time. In addition to looking around here for one, you might want to try the Facebook Trombone Marketplace or Trombone Mouthpiece Trading Post.

OP, do you know which version of the M21 you have? Smaller (line groove) or larger (coin ridge).

Here's a picture of the mouthpiece. I think it's the coin ridged kind.

That would be the larger version.

Another option that comes to mind is a Vincent Bach 7 (no C), which is deeper than the C cup version and would get a sound closer to the M21.

Like Redthunder stated, my M21 (like the one pictured above) measures as follows:

Rim ID: .984" (25mm)
Cup Depth: E, with a contour kind of like Doug Elliot's C+ cup
Throat: .228" - .230" *my #1 bit (.228") goes through the throat, but the A drill (.234") won't.*
Backbore: similar to an Elliot #2

If this is what you like, why not have it re-plated? Given variations in MP sizes, even within the same brands & model #'s nothing will get you closer to what you already know than keeping it!

Seen on eBay:
https://www.ebay.com/itm/KING-M-21-Vint ... Swq5FfaPSM