Note that the MP5 as a fluted chamber,it uses the same Roller Delayed Blowback as the G3,if the MP5 is a 9mm why does it need to have a fluted chamber when other 9mm Machine Pistols can fire fom a blowback (with no need for a fluted chamber),is it due to the nature of the Roller Delayed Blowback mechenism?



Is it because the Blowback moves the case back out of the chamber before the gas psi raises up to a point of geting it stuck to the chamber walls and the Roller Delayed Blowback delays the rear movement of the case so eventually gas psi gets the case stuck to the chamber walls?

Thank you.

ups! Sorry.

"The weapon has a fluted chamber that enhances extraction reliability by bleeding gases backwards into the shallow flutes running along the length of the chamber to prevent the cartridge case from expanding and sticking to the chamber walls (since the bolt is opened under relatively high barrel pressure)."

There are many clones out there (and here) with non-fluted chambers, and they work fine. Several of them are even Urbach barrels.

This probably only with the 9mm as it as less gas psi,the same type of non fluted chamber can't be used with a 7.62×51mm CETME/H&K G3 type platform or with the original 7.92×33mm Kurz,as the gas psi is diferent.

The Gerät 06 used a Roller Locked Short Recoil and as it used a piston/rod to force the bolt to unlock it neened no fluted chamber.
The Gerät 06H/StG 45(M) was the first to use the Roller Delayed Blowback but as it was developed from the Gerät 06 and it was a prototype for the new system it elimonated the Short Recoil and piston/rod but used the same non fluted barrel,this caused case extraction problems and gave origin to the fluted chamber,the Gerät 06 and Gerät 06H/StG 45(M) chambered the 7.92×33mm Kurz,this as less gas psi then the 7.62×51mm.

"However, the design first suffered from an inherent flaw: Without a gas vent (as used by gas-operated autoloading weapons) to relieve combustion pressure before the projectile could leave the barrel, the gas pressure from the fired cartridge would press the case against the loading chamber walls, resulting in jams. As a result, gas relief flutes were cut into the chamber, allowing the combustion gas to stream past the cartridge case and thus relieving the pressure..."

06H/StG 45(M)

Reliability, it's one less thing you have to worry about happening when you're getting shot at. Which would you rather have after you've kicked in a door?

I love my fluted chambers... they leave these great stripes on my brass so I know what's mine laying on the ground to avoid disputes.

Kidding aside, it seems to work, but I think it also makes for a dirtier trunion and receiver interior parts, with more gas in the face when you shoot with a suppressor.

The MP 38/40,as every other blowback Machine Pistols,did not use a fluted chamber.

Blowback =/= roller delayed.

i was only talking about the MP5, the subject of this thread. Sorry that I wasn't more clear.

Sorry,i was just over elaborating on the all concept.

No problem. I know first hand what happens if a rifle caliber chamber is not fluted correctly. I have one of the special PTR 91s that won't shoot surplus ammo.