I explained this earlier, but it was a while back.
The NS522 has a match chamber. The
Difference between a match and a sporter (most .22 rifles) is that the chamber is "shorter" so when some brands of ammo are longer than others, they engage the rifling much deeper than other brands. There is no bur, but if you have never had a match chambered rifle before it can seem like something is off.
Measure a round of something that is easy to chamber from rim to tip and do the same with CCI to see what I mean. Make sure you use a half decent set of calipers too. The difference may be very slight, so the ruler on a swiss army knife is out as a tool of choice here!
Here is a sweet link with your issue explained by a match barrel company
http://www.riflebarrels.com/products/chamber_info.htm