Q3131A and XM193 are Mil-Spec M193. They mean business. They are loaded hotter than most commercial loads and you're likely to notice that as soon as you fire them--especially out of a 16" post-ban barrel without a flash hider, you are going to get quite a bit of blast and a fireball. Some M193 may have flash retardant, but it's just no match for a short barrel without a hider. Prepare yourself for surgery on your ears if you have one of those short barrels and a muzzle brake. Always wear eye and ear protection when shooting!