My .30 Uragan is VERY happy with the NSA .50 gr HP-DB. Have yet to test them past 50 yrds, but 1/2 to 3/4 inch groups 50 yrds running em about 900 fps. They like a very clean barrel. That seems to be a recurrent theme with all my LW barrels and slugs. Think slugs foul em up faster than pellets. I'll run a couple patches through every 100 or so, keep it clean, especially if I'm hunting.
Still waiting to test the 55's, 60's, 65's and the VKs.
As for pellets, the Polymags group sick tight. 1/2 inch tight. Even better than the JSB 44's, which I cant really explain (??).
Another gent on here, NEairgunner? has had good results with the .30 Uragan as well.