I've got a new Hardy Gen IV mod on a new Sako 85. We noticed that the mod is blowing back and leaving carbon all over the barrel after 3 round groups were fired. The rifle was factory threaded in M14x1 and no one could see any obvious signs of damage to the mod. I just wondered if anyone has had any similar experiences? I spoke to Riflecraft and they said send it back and we'll have a look at it.