I bought a DPMS Sportical in about 2008 or so. Never really have shot it much. Before now I hadn't shot any bullet over 50 grains through it. I tried some 64 and 55 grain bullets over the weekend and actually found out those bullets were hitting the target sideways. I had it sighted in with 40 grain Nosler Ballistic Tips before and got about 1" groups with them at 100 yards. I find it odd that a 1:9 twist won't stabilize any bullet over 50 grains. I shot some 45's just to see what they were doing and the bullet holes looked like you'd expect on paper. The 55's and 64's on the other hand were apparently tumbling through the air before striking the target. Has anyone dealt with this with a 1:9 twist barrel? The gun is what I'd call new considering I haven't shot but maybe 100 rounds through it since I got it. I've cleaned it a few times over the years so I know the barrel isn't dirty. I just can't figure out why it's not shooting the heavier bullets but shoots 40 grain bullets fairly decent. Should I get a different barrel or what would y'all suggest?