Tim_W said:
When I said pressure I was not talking about to much pressure I was speaking of too little pressure for the duration time to fill on a long stroke piston even with the extra back pressure from the comp which I think is very good. The 6.8 gives relief in the peak pressure but at the same time becasue of the shortness of its pressure curve the pressure at the port will not be high end for the such short duration. The larger bore size also plays into this as well because of the relationship with volume thru a given port size compared to the 5.56. You very likely can get one to run but it will still be a challenge to find the correct balance to allow light and heavy bullets to both function.
The other thing I would be looking at is the comp on there which as I said I like: As it has a expansion chamber in there to create necessary back pressure it is very likely that it also decreases (even if ever so slightly)not simply redirects the sound signature of the weapon which the ATF is going to ruin you day about. They will claim it meets the definition of a suppressor. Not saying that it does just that from the looks and the reason for its use makes this a possibility. IMO PWS should CYA, if they have not already handled this, it and have proof of them conducting even informal sound testing. It can be attached to a longer gun that doesn't need it for function to test which would probably be easier. The same thing happened with the first of whats now called "The flaming Pig" (not what they were called or who they were made by then) and the internals had to be removed to be sold without NFA stamps.
I am not trying to be a killjoy. I am VERY IMPRESSED with this upper. I really really like it to the point I am considering buying one. I was very impressed with its perf in the video as well. I think it should be a big seller for you guys and PWS.
BTW I have been looking aorund at your site. It is one of the best laid out and performing web sites I have seen in the firearms industry. The only others close are Victor's and one other I can't recall right now. Very nice. Must have cost some to have it done.unless one of you is a developer. Regardless very very nice.
I totally understand where you are coming from. :wink:
The Comp. design concerns have already been taken care of with ATF.
PWS is already starting to ship the Diablo's out.
You are right about the pressure issues especially when dealing with such a very short barrel/system, and PWS has addressed this, but I do not want to give away their technical secret sauce (so to speak).
They are currently working on a 6.8 version, they are looking to release in the future, when they receive their special order 6.8 barrels and other 6.8 components.
I have only shot the 5.56 version, and the overall design and performance are very impressive, and for a 7" piston driven upper, the accuracy was very impressive.
