How do you remove the stock gas block on the tactical rifle so that the hand guard can be swapped out for a lighter one. Mossberg tech. says that you can not, they have a special tool for doing that. I have seen to many of these guns on you tube with other than the factory hand guards on them. So are owners drilling these gas block out and then replacing it with a after market one. The quad rail on this gun is much to heavy and big. Thanks for any help.