Bren gun gas plug keys

[Watchdog]

Hi Phil,

Utmost apologies... I have only just come across your post which asks what the gas plug keys dare used for. They should actually be referred to as: 'Gas regulator keys.' The gas regulator being the circular block at the front end of the barrel on the underside. The keys are used for reaming out any carbon deposits clogging up in the four holes on the regulator. the regulator is used to control the amount of gas tapped off from the barrel to drive back the piston. When the hole being used starts to get blocked, and the gun fails to cycle properly, the regulator can be rotated to the next largest hole to remedy the situation and restore the gas supply sufficiently enough to drive back the piston. The barrel is unlocked and slid forward enough to clear the lug an the body assembly, which then allows the regulator to be rotated - usually done with the head of a round.

Cheers,
Steve

Yep, I missed Phil's question too!

@ Phil;
If you look at Steve's pics at the top of the thread together with his additional explanation above you will have an excellent illustration of how the gas regulator block would be reamed out using the keys. There are different sized keys to fit the differing sized apertures of the gas ports.
As you will appreciate this is probably not something you would wish to do "in contact" because of the heat generated in the barrel assembly during prolonged firing! During a lull or on the ranges you could set it aside for a few minutes to cool enough to handle but not ideally when you need to maintain the output of rounds going "down range".

I know a Korean War vet who tells me that when he served as Bren gunner both he and his No2 carried a readily accessible spare gas block in a pouch or BD pocket which being clean and cool could quickly be swapped for the fouled item when faced with the enemy "human wave" type of assault as was often the case during that particular "Police Action".
Even then you would really need your wits about you, under pressure and usually in the dark!!!

Regards

Mark

[HARRY THE MOLE]

Just to make post #9 a little clearer... I've taken a few more photographs.





The first image shows the gas regulator in its housing underneath the barrel and how the body group slots in to the regulator. Before the regulator can be rotated to the next setting, the barrel has to be unlocked and slid forward far enough to free the regulator from the front lug on the front of the piston housing/body group.





This image shows the port on the gas regulator housing which fits into he front of the piston housing.





This image of the gas regulator housing clearly shows the two holes that align with the inlet and outlet holes on the gas regulator.





This last image shows the gas regulator. There are four settings, and each setting has an inlet and outlet hole. In total there are 10 holes to be cleaned out with the keys. Under normal circumstances the barrel fitted to the gun, and the spare barrel - which is swapped over every 250 rds when in action - would be sufficient to give trouble free operation. On one occasion me and my mate put two cases of magazines (672 rds) through a Bren and spare barrel at full auto without having to re-set the regulator. But when in combat it would be a different matter, and that was the whole purpose of the regulator - to overcome any fouling of the ports and keep the gun in action with minimal down time. Carrying a spare regulator would make good sense.

Cheers,
Steve

[Jb4046]

Happy to add my own set finally to my Bren collection! Why these are soo scarce I haven’t a clue

[HARRY THE MOLE]

Its nice to have all the tools for the small parts tin - even though you will never need to use them!

Cheers,
Steve

[Dirt Detective]

Why rare? I went to an estate sale today and picked up this wood box filled with these Bren Keys..I will sell for $10 a set will try and post pic of box in a bit.

[Dirt Detective]

Here are pic's of keys

[HARRY THE MOLE]

That's handy to know!