Its a tension barrel with double carbon sleeve. I had high hopes for the nsa 26.8gr, the smack at 30 yards on steel at 1094fps was awesome! They held about .4” at 30 and about .7 at 60 so not terribly bad. Overall Im happy with it. Shoots the 34gr jsb at 960fps and well under an inch at 100 and is starting to show promise with slugs. Plus its lighter! Everythings threaded, no more stupid grub screws.