I am looking to get my first AR and am leaning toward a colt. I want a rifle with a front rail, but I think the 6940 only has a factory 7" rail. I am concerned I will regret having only a 7" rail in the future as I add grips, flashlights, etc. How much work is it to add a 10" floating troy front rail to a 6920? Does the barrell have to come off? Does this require any special tools? The total prices would be about the same and I could get the rail I want on the 6920 vs. the factory 7" on the 6940. Thanks! CB Wanna kill these ads? We can help!