The dimensions for the 17 HH arnt out just yet, I have an email out to Pacific as soon as they get them I'm going to have a reamer ground. The easy way to go would be to find a take off barrel from just about any bolt gun, the 342/340 barrel is kind of small so a take off barrel can be turned down cut back and rethreaded. In order to get the barrel nut off all you need is a 1-3/16" wrench slide it over the nut cut some 1/8" welding rod or brassing rod in 3/4" inch chunks all you need is four of them. Slide the wrench over the nut slide the short chunks of wire into the slots in between nut and wrench. Of course you need the barrel or action clamped down. What I'm describing here is what I did to an 840 to build a 17 Fire Ball, came our great, shoots great and I figure I have less than $250 in a 17 FB.

Bob