Hi Matt,
"MA", when used alone: BiaB types small "M"+"A".
Most of the other "MA plus extension"s (like MA7) are single characters.
A little similar with "MI" (the symbol "-" in PGChords.ttf).
But that is not essential with respect to your question. Any subscript sign after the superscript flat-sign "b" will have this much space, until I prepare kerning tables, which remove too much space between selected character pairs (typical example is "A" and "W" - what in music notation is rather rare :-)
I will add kerning tables for selected character pairs later, when all the design works are done. And please do understand that I will not publish the font, as long as Peter Gannon has not give his "okay". He likes the font as well, but he has not yet come to respond to my last emails regarding supporting the font in BiaB - which means allowing the use of other fonts when "Jazz Symbols" is checked.

Biab/RB latest build, German Language Pak, Win 10/64 Pro, 1 TB SSD, 32 GB RAM. Notation SW Finale, StaffPad, SmartsScore – Playing Double Bass, Guitar, Piano