Hi,
I'm trying to find out what should be the facing lengths for Berg Larsen mouthpieces. Which should be the specification? I'd appreciate a table with the "must be" facing lengths for each tip opening in both "M" and "SMS" models. The best I found was a list of values here, in this group:
...
facing lengths (to the .0015" feeler)
Sop 34-40
Alto 40-44
Tenor 44-48
Bari 48-52
...
I could supose the minor value could be the "SMS" value and the bigger value the "M" value if using this values for Berg Larsen mouthpieces. Am I right?

Thank you very much in advance,
Luis Pablo
 

I have done reface work on about 30-40 Berg Larsen, mostly tenors. All (!) had conveks tables and almost impossible to find where the facing was supposed to start. Most were SMS a few M - but I can not see that there is no difference between them.
 But again: The mpc that players sent to a reface is not the good players with flat tables and nice facings :-)

Thank you for your reply Efurre. What's your prefered fecing lenght when refacing these mouthpieces?

It depends of what the client prefer. 
 But when I look at my sheets most tenor HR facing lenght are 46 - 48. Metals a little shorter. The baritone players I have work for have been on Larsens for years, so that they seems to like long facings. The laste one was the HR Berg Larsen for my former teacher. The lenght he liked best was 55. Here is he and that particular mpc: https://youtu.be/GDyrNG_TR6E https://youtu.be/GDyrNG_TR6E