Thread: Suppressed 9mm

Here is another project that I have been working on, I took a new 410 and re-barreled it with a length of 9mm barrel, then fitted a full length can including K baffles in the end section.

The idea of the porting was to try to drop the velocity of standard 115 Gr and 123 Gr ammo to subsonic levels (inspired by the MP5SD), however the porting is closer to the chamber with the SD and at the closest distance to the chamber I can get with this I am finding that they are still supersonic.

That said whilst not that accurate I found using standard 147 Gr ammo it is staying sub sonic and is just soooo quiet, you really do just hear the hammer drop.

Other thing I noted that with the standard 115 Gr and 123 Gr ammo whilst not sub sonic so you get the sonic crack, the actual suppression for the shooter is great and not hearing protection required, it also seems bloody accurate with this easily under and inch at 30 yards.

To make life a bit more interesting I made the 9mm chamber reamer which came out great and produces a good finish well within the SAAMI specs.

I should note that obviously I have note fitted and extractor yet but will do before its finished.

Note the the tube extension to the 9mm barrel is to comply with legal length requirements if you were to ever try it without the outer can on, though with the extensive porting that is not really feasible....just something the local Arms Officer wanted.

More experimenting to do but an interesting path.

Cheers

Oh to have those skills and the gear to employ them. Nice job!

Originally Posted by Jhon

Oh to have those skills and the gear to employ them. Nice job!

Thank you

great build...now what would happen if you kept going 1 row at a time extending your porting??? do you think it may bleed off more blast onto rear of projectile and thus drop your velocity the desired amount???your barrel must be plurry short before the rifling and continue similar distance after it...my thinking is the blast up projectiles bum is still pushing it a bit once past your porting....maybe.....

or alternatively....asuming you have got more barrel...a longer barrel might bleed off the speed as it does in .22lr if projectile reaches optimum speed in say 12" of barrel,any past there is slowing it back down....or so the barrel chop experiments seem to show.

Yea barrel as such is short at around 190mm as trying to get four guns out of a barrel blank also if you look at this being a pistol round it is still a reasonable length for a pistol or SMG. This is the second one I am trying as the first one had more ports and going further down the barrel as you say but also had the same results, hence I researched the SD and followed that path. I think the thing is that the SD has ports around 30mm past the end of the chamber whereas the closest I can get with this one is about 60mm. I think its that pistol power burns super fast and I wanted this to work with standard ammo and get into reloading. That said it is the biz with 147Gr

you will crack it......just keep at it.

If you reload you could reduce the quantity of powder behind the 123 gr till you reach sub speed and be even quieter ( less gasses to push a smaller mass)

Originally Posted by Friwi

If you reload you could reduce the quantity of powder behind the 123 gr till you reach sub speed and be even quieter ( less gasses to push a smaller mass)

Yes for sure but the idea was to be able to use off the shelf ammo.

A bolt action in 9mm would be a great project. Considering the low pressures i guess a tube gun would hold up?

Originally Posted by 300CALMAN

A bolt action in 9mm would be a great project. Considering the low pressures i guess a tube gun would hold up?

Yes been on my mind, I need to keep an eye out for a cheap donor gun to convert.

My experience using a suppressed Marlin Camp before the great confiscation was that subsonic 9mm fails to expand the projectiles. Drilled pencil holes in goats and they kept running. Finding a good projectile and hand loading will be key to making it an effective hunting gun.

Have you considered making a .410-9mm chamber adapter?

Originally Posted by longshot

Have you considered making a .410-9mm chamber adapter?

Yes a friend got a set a while back of various calibers, not got round to making one yet though, we could also do for 32 acp. as they run ok in old 303 barrels off cuts

Originally Posted by Fssprecision

Yes a friend got a set a while back of various calibers, not got round to making one yet though, we could also do for 32 acp. as they run ok in old 303 barrels off cuts

Yes, works well. Have a footlong 12G adapter made from a .303 barrel but after making I got stung $50 for a box of fifty .32 ACP, no doubt flying fast out of the footlong barrel instead of some short-barrel pocket aberration.

The next one I might chamber in 9mm with a gradual throat reamed in, to squeeze 9mm lead bullets down to .303 and thus have better BC bullets emerge at slightly higher velocity (anyone remember the Myra Extruder?). Lead ball 9mm is much cheaper than .32ACP.