The Pr.27 "Mashina" design was based off the sionics mac suppressor as originally sold with mac 10/11 submachineguns.
The suppressor was intended to be used as a grip, hence the awful ergonomics of an unsuppressed mac.

The 9mm version has been tested by many users, but we have not formally melted it down.
As of yet, the 5.7x28/22 and 45 versions remain untested.
The efficacy of it will depend on the materiel it is made in.

As always, if you plan on using for anything but fun, make it in something nice.

There is also a flash can version for those who want the look and feel but are too scared to make a real suppressor. Instructions for assembly are the same.

I have included the files for .45acp, 9mm, and 5.7x28 overbores.
The 9mm overbore has been loosened by about 3 percent to try and avoid droop-induced baffle strikes in high ROF.
ONLY use the tight bore option if you are going to be shooting normally and DO NOT put your hands on the tight bore version.
To be very specific, the overbore on the "tight bore" is the same as all of my other 9mm releases.
Others have not been treated similarly, so use carefully.

If you are very confident in your printer and everything being up to snuff there is a normal overbore version in the files as well.

no I will not make a version with some kind of head for a wrench to grab on. It ruins the asthetics dummy. Don't be a pussy.
I will also not make a version with different threads than what I have already done.
The pr.27 is most effective when utilizing the mac 3-4x10 and 7-8x9 threads.
1-2x28 make a poor substitute and no other direct threads make sense to use.