Sort of. It turns out that SRT makes exactly what I'm going for:
http://www.srtarms.com/mkii.htm
I want to avoid using packing. That stuff fouls up too quickly. Too much maintenance and it is so 1942. I haven't made a model of the design yet. What I am looking at doing is removing the front sight and turning down the barrel. The rear 3/4" and a section in the front will only be turned down to the ID of the main tube. The muzzle will get a 60 degree crown for spreading the gas into the blast chamber. The middle part of the barrel will be turned down to about 1/2" OD and get some ports.
This will constitute the rear chamber. In front of the muzzle it will look a lot like a standard muzzle can that is rather short. There will be a small blast chamber with blast baffle. Then a series of slant baffles followed by the end cap. I don't have a precise baffle count yet or precise location and size for the ports. I'm thinking about using an eight inch tube. If I go with a shorter tube, I will also shorten the barrel a bit.
The rear chamber will be sealed from the front chamber. So when gas goes through the ports, it has to go back through the ports to exit. Effectively this makes the barrel seem longer to the front part of the suppressor which is why it can be shorter than a typical muzzle can.
I'll use a chronograph to help size the ports. I'll shoot some rounds over the chronograph before porting to get a starting velocity. Then I'll start the ports. Then shoot over the chronograph again. I'll enlarge the ports as slots, making them longer each time I shoot over the chronograph until I start seeing the velocity go down. Somewhere between 5-10% I'll stop and that will be the size of the ports.
As for where I start the ports, it looks like from the data Artful pointed me too, I am safe starting about an inch from the muzzle and working backwards. Using slots will help me around the problem of gas making a 90 degree turn which is something it doesn't like to do.
I'll document the process so that however it works out, F1 can makers will know if they want to imitate that design or go in some other direction. The design is rather simple and you can be sure that I'm not sure if it will work or not.
Before I commit to cutting a perfectly good MKII barrel, I plan on making a short muzzle can out of delrin for a Marlin with 22" barrel to make sure that the front portion of the integral will work. It should be simple enough to make a throw away can out of delrin and I will also get an idea about how many baffles I actually need and what sort of length is really required to do the job.
The volume of a 22" barrel is a bit under a cubic inch. Obviously a 5 1/2" barrel (which will get shortened slightly by the crowning) is somewhat less. The porting in the integral simulates a longer barrel except the work of pushing a bullet through the longer barrel hasn't been done. So the muzzle gas in the integral is still going to have more energy than the muzzle gas from a rifle length barrel.
The reason barrels get ported and shortened in integral designs is not to slow down the bullet but to allow more volume for the can in a given length. Slowing down a bullet that is already subsonic anyway doesn't do anything for suppression. It's the gas that needs to be slowed down. The exception to this is when bullets go into the transonic velocity range (starts at about 1089fps depending on conditions). The bullet flight noise starts to get a lot louder with each foot per second until it is fully supersonic. At that point, the bullet flight noise is constant and quite loud.
Preserving most of the muzzle velocity allows one to choose a load based on noise and velocity. Remington Subsonic ammo is good for quiet shooting. Standard velocity will only be a little louder and you shoot a heavier bullet. High velocity will go even further with more energy but risks the ballistic crack.
Hybrid Mode
