Thanks for the info on the background of UM1. I am lucky to have about a half case of UM1/UM1B, and another half case of the UM22. From what I have been able to put together from a variety of old threads, the Federal ammo for the '92 Olympics was 226M, and most of it was made in batches tuned to individual shooters and their equipment. The UM1 that followed commercially was available from '92-'96 and definitely was a higher velocity product. I have chrono'ed 3 lots of that and most are in excess of 1200fps.
The UM1 was superceded by 1000B from '96-'99. I have never had any of this so can't speak to it from experience.
UM1B was offered from '00-'08. It was marked as 1080 fps on the box. I haven't chrono'ed this, but by ear it is definitely subsonic, and for me shoots similar to Midas+. This suggests that Federal may have finally heeded the feedback about UM1 being "too hot."This was the end of the blue, white & gold packaging & the end of the dimpled cases.
UM22 was sold by Federal, but loaded by RWS and packaged in the familiar red/gold/black boxes. It was produced from '09-'15. Interestingly it has a Federal "F" headstamp on the flat undimpled base, which seems to indicate that Federal supplied primed cases for RWS to load. This was the last of the true "match grade" Federal .22lr ammo and it continued the nominal speed of 1080 fps from the UM1B. One sometimes encounters speculation that UM22 is essentially rebranded RWS R50. It certainly shoots like R50 of similar vintage for me. But the use of F headstamped brass suggests this is not the full story on the UM22 pedigree.