I agree with the two posts just above this one. I tried the Al Hirt Jettone and it is a difficult playing mouthpiece. It is made by a different Jettone company than the one back in the 70's. I tried this newer version Jettone out about a year ago, when I thought I lost my 70's version Studio B that plays so comfortably and like a dream.
Yes, the older version is shallow as well, but perhaps its the rim, the thing has a super range ability from top to bottom. You can tell the difference in old versus new as the older version has "Jettone" written in italic.