Colt HBAR question

[Mighty_Mouse]

I have a older Colt Sporter Match HBAR, when you cycle the bolt by hand it is extremely smooth, I have compared it to other ARs including higher end ones and it's not the same. I'm building another AR and want to try to recreate this smoothness, I know the bolt is not a M16 bolt and the ramp on the bottom of it is more tapered, also the HBAR has a rifle length extension tube, spring, and longer buffer weight that rides on 2 locations in the tube rather than 1.

It might be stupid, and it won't improve the function of the rifle, but does anyone know if it's these parts that make the difference or something else Colt was doing back then, any info would be appreciated.

 

[AKguy1985]

Does it have the half moon bolt carrier?

 

[KurtM]

Colt used extruded aluminum buffer tubes, not machined tubes that were bored out and lath turned in their rifle length buffer tubes. The result was an extremely smooth interior tube finish, hence the smooth feel. I've lost track of who extruded tubes but a search might help.