I posted some details about this here: http://www.ar15.com/forums/t_6_20/467264_Carbine_or_Middy_length_for_cutting_barrel_and_deticated_can_usage_.html





It depends on what the port size is of the 14.5" barrel is now.


As I mentioned in the thread mentioned above:


>>>>>>>>>>>>>>>>>>>>>


Likewise, a factory Colt 14.5 or 16" carbine barrel is ported at .0625"
while many other commercial 14.5 or 16" carbine barrels are ported at
.063 and larger.  For a dedicated carbine build I would be more about
.046 or .049 for a 12.5" carbine.


>>>>>>>>>>>>>>>>>>>>>


I think for a Colt barrel at .0625" would be too small for a 10.5" unsuppressed.


If you don't want to go adjustable then work your way up in your barrel's port size with the weakest ammo you plan on running till it performs the way you want with your configuration.


However, note that even at .0625" that is a lot bigger than .046 or .049 than we use for the suppressed mode so maybe just try it suppressed at that size and see what you think.  Everyone is different in their tolerance of gas blowback.  I find running a 10.5" at a .06x port to be very unpleasant with


1. the amount of gas to the face


2. increased fouling coming into the action


3 and increased recoil.  


However, those may all be at acceptable levels for you.  You have to try for yourself to see what you think.


I'll also mention that it is hard to convey the difference of what it is like to run an optimized suppressed port size.  It is a much more pleasant experience in the smoothness of the rifle.  Like you've gone smaller in caliber and it really is like you've changed the length of the gas system from a carbine to even longer than a rifle length gas system since the port is now configured for the dwell time equal to distance from the barrel's gas port to the end of the suppressor instead of the end of the barrel.





 

Pretty sure it won't even kick the brass out at .049".