If so does it function reliably with subsonic ammo? If so could you please tell me what the gas port size is on your upper?thanks in advance John

No I don't have one right now, but check out this thread: [url]http://www.ar15.com/forums/topic.html?b=3&f=118&t=165128&w=searchPop[/url]

Quarterbore is a good man to talk to about the 300Whisper.  

There are a bunch of us who ordered custom barrels from a guy, but it remains to be seen if we will ever see those barrels.

Model 1 sales or someone like that has an Olympic (I believe) brand 300 Whisper barrel listed on their web site.  I think it was 1-8" twist for $170+