Whilst on a lock change in Wednesbury this morning I got my hands on an Abus 3 star lock cylinder. I have fitted the Maco 3 Star version, which is in fact identical but they're pretty pricey so I haven't given any the destructive test until today.
The Abus 3 Star locks feature a robust central cradle that houses the cam section of the lock, a sacrificial front section and all the usual anti-pick and bump features you would expect of a three star lock.
I set myself up in the vice and using my grips on the front 10mm of the lock (as in a real world scenario you shouldn't really have access to more than that) and began the snap test, expecting the front section to sheer off to begin with. I was surprised to see the entire cast section of the lock snap off right up to the cradle which allowed me to open the lock with a flat blade screwdriver!! I was pretty sure that should not have happened and kicked myself that I had not filmed it.
I flipped the lock around and set up my camera this time, again only using the front 10mm of the lock cylinder and snapped it again clean off at the cradle (Click here for Video). The central cam did not lock up in any way and allowed the cam to turn freely. Okay we could argue that there may be an extra bit of plastic or wood lipping further up the cylinder and thus dampening the force closer to the centre of the cylinder, however looking closer at the snapped sections there is no sign of fracture near the designated sacrificial cuts.
It seems the Abus 3 Star lock cylinder has not been designed for horizontal snapping forces and the lock is clearly weaker at this point due to the additional material removed for that final pinstack and the two horizontal securing pins. It really was an unexpected and exciting result from a tried and tested three star, kitemarked cylinder.
I have only tested this one cylinder so I can't really state that these locks are not fit for purpose, but if this attack can be replicated in a door on other Abus 3 star cylinders then I really think the need downgrading to 1 star. If more material were to be removed from the sacrifical cut then they may pose more of a problem. A reliable locking cam mechanism really needs adding in place of the free floating cam currently used which is in fact vulnerable to wire bypass attacks anyway.
Locksmiths! If you have some old Abus 3 Star locks then I would be interested to see your result. Please film it and I will upload with your results. Cheers.
A few authoritive sources have been in touch stating this lock is about to lose it's 3 star rating for the very reasons highlighted above. Seems like a wise move until the design is brought up to date.There are much better upvc door locks nowadays.