Can someone tell me if a GI NM unitized gas cylinder, in your opinion, is worth the cost. Does it have much of an affect on accuracy? Does it have to be used with a NM barrel, or will a standard barrel accomodate it as well? Would it be worth the cost / trouble for an unbedded rifle? Is there anything I need to consider before deciding on the installation? I realize that you can use shims instead, but I prefer not to go that route. Thanks in advance for your help.