Ive the older Sam Yang Sumatra w/ a .2525" barrel. Both the NSA .249" and .250" work, some weights better than other depending on speeds. These 29g dish base work great for me ( a little better than the flat base) at a avg of 1080 fps, power level 3 (max is 4) at 180bar. Tuned for 210bar in general. Shoot 1 atop the other at 100 yrd, a nickle sized silver spot on a black steel plate. If i push them faster or slower they will open up a bit but still tight. If i want to shoot 135 yrd, i have to really adhere to these speeds. At 160 yrd i can pull off 2 inch groups reliably. They shoot very flat. All the .25 cal NSA work in my Sumatra. A matter of how good i am on a certain day. This is after a Will Piatt tuned and trigger job that made a world of difference. Before he worked on my trigger the results were considerably different. I gobbled up a box of these fast. My happy medium and fav is the .250" 33.5g for long range targets and the 52g boat tails for actual hunting. But these work fine and if the 33.5g wernt available id order more. Outstanding consistently in weight/diameter. At this weight and speed, still kinda loud even w/ a Donny Fl Sumo LDC, but not loud enough to spook my horses. A consistent 75fpe average on the above settings at 15ft from muzzle. I can push them to 1130 fps for 82fpe for "up to 25-30 yrd" for bigger critters, past that, gotta put the brakes on just a tad for 100 yrd fun. Excellent product=normal for NSA. Quick delivery!