i have a savage mark2 chambered in 17hm2, i love the gun but there is one major problem with it. about 5 out of 50 shots it will split the shell case and it gets stuck in the chamber. its easy to get out you just take a pocket knife and slip the blade under the rim and pop the casing out. i dont know what is wrong with it, been like this since i bought it new. like i said, not a big problem but it gets really annoying. what could be causing it?