I took my Cooper M38 in .20 Vartarg, loaded with RL-7 and Nosler 32gr BT's at 3,680 fps. It seemed to do the job quite well:

The country is pasture mixed with rock piles the chucks just love do den up in. This is a typical view of the area; the rock pile way in the center background had a huge one on board that met a 32gr BT in the morning shade:

I was amazed at the damage the little cartridge can deliver on a critter the size of a chuck inside 300 yards. This is typical terminal performance:

Average shot distance is about 250 yards, so after shoting ground squirrels at 400+ days earlier, chucks appear huge in comparison. The little Vartarg was perfect for the area, as there's nearby houses on small ranches that don't want bigger boomers about. This little ."204 Lite" is really becoming a personal favorite. I'm liken' it alot. It's like shooting a 450 yard capable pellet gun.
