Picked some up for reasonable-under-the-circumstances, at a point when .22LR options were slim and more to the point, overpriced. By a lot.

Man, is this stuff dirty. I had two FTEs in the second magazine, broke down the MkIV to check the barrel - because isn't that the joy of the MkIV series? A dozen rounds had left more crud in the barrel than a hundred CCI. Started alternating mags, running CCI standard every-other to clear things out - which it did, nicely. None of the wax-sticking issues I had over winter in 20 degree cold. Go figure.

But. It did seem to group better.

Interesting. An LGS has had the Norma TAC last week, and I picked up a box to try it out. I've also got a Mk IV, so when I try it I'll see if it's dirty in mine.

It worked fine alternating brands. My range officer has had similar issues.