graylion said:

5.5" is very short :) I was not aware of that. My idea was not a longer barrel, but a very short gun for SF. Doesn't have to be AUG. Also I was and am envisioning an integrated silencer that is big enough to actually silence the gun, which, from the pictures I have seen is a fair bit longer than the bbl. This would make the gun something like P90 in length - fully suppressed

It's certainly doable.

The ar15 bullpup conversion, paired with a SIG MCX 5.5-8"+ suppressor, would be pretty simple albeit expensive to have done up.

Take something like this, handguard that goes over the suppressor, bing bang.

Here's a CZ Scoprion 9mm bullpup with 7.7" barrel. Terrible here, but with a suppressor and some sort of VFG or handguard could be ok.

Both of those things are awful.

And to what benefit? For control of the weapon, the centre of mass should be between your hands.

Reposting, years after the first time, because it’s still very persuasive:

https://anarchangel.blogspot.com/2005/03/why-bullpups-are-persistently-bad-idea.html

just spoke with a serving soldier in the Irish Army, who said this when I asked him about the AUG:

"Excellent ergonomics, Great for handling ranged and close quarters and is quite reliable in my experience.. Most of the flak Bullpups get are from Americans civilians who don’t use them."

graylion said:

"Most of the flak Bullpups get are from Americans civilians who don’t use them."

LOL.  Most of the world's armies do not want to use bullpups. 

And special forces typically prefer a conventional configuration.

Australia, for instance, recently adopted a SIG SBR in .300 BLK for SF units:

That's despite the fact that the F90 PDW could easily be chambered for .300 BLK and fitted with a suppressor.

Land Forces 22 - More Weapons from Thales - Soldier Systems Daily

Note that .300BLK when chosen by the military is to meant to replace the 9x19 , so MP5 , not 5.56x45 weapon. 

Australian SF also used 5.56x45 carbines in preference to the general issue 5.56x45 bullpups.

YouTube

AUSTRALIAN SOTG SPECIAL FORCES - 2 COMMANDO REGIMENT - HELMET CAM COMBAT FOOTAGE - AFGHANISTAN

Commandos from the Holsworthy based, 2CDOLeaked helmet cam footage.

YouTube

Australian Special Forces in Afghanistan (archive footage)

Australian special forces (SASR/2nd commando regiment) helmet cam footage from AfghanistanArchive footage "From the Shadows: Australia's Special Forces" docu...

stancrist said:

Australian SF also used 5.56x45 carbines in preference to the general issue 5.56x45 bullpups.

And French SF are also using 5.56x45 mm carbines instead of the FAMAS, but in the case of the French SF, (and I think it's also the case of the Aussies SF), one of the main goal is not to carry a big "we are French" or "we are Australian" tag.

EmericD said:

French SF are also using 5.56x45 mm carbines instead of the FAMAS, but in the case of the French SF, (and I think it's also the case of the Aussies SF), one of the main goal is not to carry a big "we are French" or "we are Australian" tag.

That sounds absurd, more like an excuse to justify the needless purchase of what they want to use.

I suppose that UK special forces also uses 5.56x45 carbines so as to not carry a "we are British" tag?

In actuality, Australian infantry (and later cavalry scouts, special operations troopers and clearance divers) have used M16A1 rifles since Konfrontasi (aka Operation Claret) prior to Australia entering the Vietnam War. The AUG was selected over the M16A2 for manufacturing reasons in the 1986 small arms replacement program. At the time the SAS & CDO troopers who were part of the testing program preferred the M16A2 to the AUG. School of Infantry instructors preferred AUG.
To be completely fair, there are 3 acknowledged reasons for the SOCOMD preference for M4:

1. Maritime operations - the gas piston and operating rod assembly in the F88 is difficult to drain and submersion can render the weapon inoperable for a time. The M4 is ready to use after a few seconds drainage.
2. Modularity - the M4 was adopted along with elements of SOPMOD (I) including the KAC RIS. At the time, the F88 predominantly was issued with the fixed carry handle 1.5x scope and has little ability to integrate weapon mounted ancillary devices.
3. Reliability - the initial production F88 had some reliability issues* which soured SASR & 1 CDO on the F88.

Ergonomics is not cited as a reason for SOCOMD selection of M4 rifles.

EDIT: Nor is deniability of nationality.

*The reliability problem was traced to clearance between the operating parts and the seam weld in the stock, the TDP and the Steyr assembly process didn’t match. The Steyr stock manufacture workers removed material greatly in excess of the TDP, ADI held tight tolerance to the TDP and there was impingement from the weld into the path of the slide which resulted in erratic bolt closure. Altering the TDP to specify sufficient clearance resolved the problem.

stancrist said:

LOL. Most of the world's armies do not want to use bullpups.

And special forces typically prefer a conventional configuration.

That is the poorest possible argument imaginable.

Its in the same league as "children allways want pizza or sweets, so pizza and sweets has to be the ideal food for children."

Soldiers are only experts (if at all) in soldering. They are NOT experts in firearms technology, physics, logistics, engineering etc. Furthermore they can not want something they do not know about or don't understand. If you ask soldiers what they want and really try to start a program to get it you end up with desasters like Puma.
Two brand new examples: The RHIB for the KSM replacement debacle and the new moronic handgun policy of the German armed forces.
In the first case the SF guys where asked what they wanted and needed to get the best combat boat ever... the result has been an impossible list. In the sense of basic physics would be violated as well as a complete lack of foundation in modern engineering. The resulting cluster f*** resulted in the program to be terminated last week and the starting of a investigation by MoD.
The new handgun policy is that every soldier now gets a pistol and two reloads regardless of his other equipment, weapon and function.
Reason: the soldiers asked for it... because they did not understand why only special personell gets issued handguns. The second argument is: "to have a means of last ditch defense when you run out of ammo". Which is the dumbest thing I have heard in a very long time. A loaded P8 comes at roughly 1 kg. Two loaded 9x19 mags are roughly 1/2 kg. A loaded 30 rds mag for the G36 comes at roughly 1/2 kg. So the soldier exchanges three additional 30 rds mags for his primary weapon for 90 rds in total for a weapon of highly questionable combat effectiveness with 45 rds. If that doesn't make sense. Especially if running out of ammo is the issue.
It gets even dumber if you think about machine gunners or soldiers armed with MP7. Yes these also get a secondary pistol. Everyone gets one. So nobody feels left out. If anything IMHO this is a reason to never again ask any soldier. The level of stupidity and ignorance is staggering.