Which type of autoloading action is the quietest in theory?

[hjustein]

For instance, on a subgun, assuming equal calibers and barrel lengths, I am guessing that a locked breech is theoretically capable of being quieter than a blowback action. So an MP-5 or a TMP would be quieter than an uzi or a MAC using the same can, ammo, and BBL length. Is this true?

On rifle cartridges, pretty much all are going to be locked breech, so basically you have piston and direct impingement operation versus roller locked operation. Which of these systems is queter? I am thinking roller locked, then DI, then piston. Does anyone have any experience to back this up?

My basis for these guesses is that the actions that don't vent any high pressure gasses are going to be quieter.

Do roller lockers vent gas in the chamber area from the flutes?

Somebody help me out here, I am trying to decide what platform I want to suppress.

thanks

[Crosshair]

I have no idea, but I would have to say that short or long recoil would be quietest. No gas is being vented to cycle the action and little if any gas escapes from the breech. Personaly, I would say long recoil over short recoil since the breech remains locked longer.

[beerslurpy]

Blowback is better because there is no gas vented and no other parts moving, only force being exerted upon the bolt by the cartridge.

To move the bolt, something will have to act upon it. All other methods are either varieties of blowback or noisy gas actuated systems. I count direct impingement as a hybrid system since it uses gas to unlock the bolt, at which point the bolt is pushed directly back by the cartridge.

[chili17]

I would have to go with OB smgs with a heavy bolt (not macs).

sterling mk5, UZI,swede K are about the quietest centerfire firearms I have heard (all shot dry).

HK MP5SD and M16/9 all seem a little louder than the above to me.

[Golovko]

...I count direct impingement as a hybrid system since it uses gas to unlock the bolt, at which point the bolt is pushed directly back by the cartridge.

Actually, by the time the bolt is unlocked, the pressure is already too low to cycle the action via blowback. Like conventional piston actions, it is the recoiling bolt carrier that unlocks the bolt and then "drags" it rearward to extract a cartridge.

[hjustein]

Ok, but the M16/9 is blowback operated. Are you saying that the bolt is light enough on it that the action is opening while there is still high pressure gas in the barrel? So following this logic that the heavier you could make the bolt in a M16/9 the quieter it would be.

And why would the MP-5 be louder? Does it unlock quickly relative to the heavy bolt blowback? The roller locks can be adjusted for unlock time cant they?

Anyone ever heard a suppressed TMP?

I would have to go with OB smgs with a heavy bolt (not macs).

sterling mk5, UZI,swede K are about the quietest centerfire firearms I have heard (all shot dry).

HK MP5SD and M16/9 all seem a little louder than the above to me.

[renegade]

The longer the breech is closed the better. Outside of locked breechs (bolts, levers, etc.), delayed roller-back seems to stay closed the longest. Blowbacks unlock the fastest, actually before even being locked. However a low RPM heavy bolt like Uzi would do well.

[Arsenal]

Gunshot sound wise, a chaingun or minigun would be quietest because the chamber closure time can be managed independently of the chamber pressure via motor speed and rotor cam angles - the entire firearm feed/fire/eject cycle is independent of the internal ballistics.

Conventional autoloading firearm designs all require an unlocking / ejection sequence to begin while enough energy remains available to complete the cycle - from a sound signature perspective that timing may not be optimal.

[Fargo]

Without a doubt, the Walther P22 has the most quiet action I have heard on a semiauto.

[Artful]

Without a doubt, the Walther P22 has the most quiet action I have heard on a semiauto.

Zinc doesn't have that steel ring to it

For what it's worth my HK has lots more dirt with a can on it so I'd say it's openning while residual pressure is still in the barrel. I like to see a chain gun with a suppressor that would be - I know Gatling guns aren't considered Machine Guns wonder if you put six pack of suppressors on a six barrel gatling gun what it would be like.