MFS stuff is just fine - I watched guys go through the 2 day VSM course using it with no problems either with accuracy or reliability. I've started using it myself, since it's roughly equal to reloading in cost. It is NOT steel core, and while a little (very little) dirtier than Rem-UMC, doesn't get your gun dirty enough in 500 or 1,000 rounds to cause anything remotely approaching an issue.