No factory loaded varmint rounds for the 280Rem. That's one reason I chose to get a
270Win. several years ago. Of course, there's only one for the 270Win., the 100gr. by Remington, but as luck would have it, it shoots pretty good in my rifle - about 1" to 1-1/4" at 100yds. Should be good enough for most shots at chucks, coyotes, etc.
The rest of my "varmint" shooting is left to my Ruger 77/22 target rifle in 22mag.
A bit expensive IMO, but one option you might try for the 280Rem. is custom ammo
at Conley Precision.
Link:
http://www.cpcartridge.com/index.htm