I got some 29.5 NSA 25 cal slugs that my FX Impact MK II really like at 972 fps. 1 inch groups at 100 yds. and about 1.5 inches at 150 yds. These are the first slugs that really shoot well. In the wind they are really good with as much as 2/3's less drift in the wind over JSB King Heavy MKII. So Decided to test the expansion on the slugs so I took a 3 litre plastic soda water bottle filled completely with water and set it out 80 yds. and the result well lets say no so great. No Expansion just compressed the slug to about half its original length and thats about it. Iam sure penetation is alot better then pellets as far as that goes but was hoping for more expansion of the slug. The piece of plastic from the bottom of the bottle and the slug was both inside the bottle which made for a easy recovery. What do you all think about this have you had same experiences or not.