Lentamentalisk wrote:If you make your suppressor that extends backwards only be on the top 3/4 of the pipe (so as to avoid the chamber) then you could extend it almost all the way back.
On big problem with that - it's meant to be removable. How will it be fitted to the muzzle? Neither a twist lock or a threaded connection would allow that.
The other thing is that these fittings need to double for both the breech load and semi-auto configurations. The breech load barrel is twisted through 90 degrees to unlock it - the suppressor, being fitted to the barrel, will twist with it, crashing into the chamber.
For those reasons, the suppressor cannot extend back past the end of the chamber.
ALIHISGREAT wrote:and i would just use a threaded fitting instead of 'twist lock' so weight isn't much of a problem.
"You would" being the important term.
Personally, when I've looked into it before, I find threaded fittings like that on the muzzle pretty ugly.
Aside from the higher practicality of the twist lock, it taking me no longer than an instant to change over two fittings (it being a mere quarter twist to fit them), such as the porting, suppressor or muzzle brake - if I'm using more weight than the twist lock can with stand, it's already too much, because it's creating an unnecessarily large moment on the barrel.
Even disregarding that, I have several attachments already which use the twist lock which I don't want to throw away.
@JSR: It's not really a line of sight issue (although obviously I don't want a problem in that area) - it's a weight one.
Taking things into account, and with a looped-back moderator, I think I can manage a suppressor of a volume of about 1200 cc, a little more than the combined volume of chamber and barrel.
This isn't a truly appalling volume, but it's not exactly huge when you're trying to quieten down around 23 litres of air all trying to escape the muzzle at the same time. (Interesting trivia - this actually means that 3vo uses roughly twice as much mass of air as the mass of powder in a .50 BMG round)
In a theoretical flow ideal, that means I can drop the pressure at the muzzle to as low as 6 bar. There's still a lot of gas volume, but I suspect I can reduce the sound considerably.
Still, I'm still trying to find ways to make this volume count for more.
Oh, and with regards material, I'll be making it from PVC sheet.