My experience is the XM stuff is OK,
But the IMI is far and away, better ammo.
I had lots of blown primers with both XM855 and XM193.
None with the IMI M193 or any other 5.56 or 223 pressure loads in my rifle (loose Wylde chamber).
IMI has a lower flash signature and generally good appearance and lack of visual defects compared to XM.
Bookmarks