Master 931 Gut shot
I have managed to pop it about 4 or 5 times but it has always taken a while. Probably just lucked it.
Recently I got it out again to have another go and as soon as I’d raise a pin or two it would lock solid. I knew that it had a couple of spools but even if I managed to rotate it on a spool/s it would lock up solid. No counter rotation, no feedback, just “all locked up”.
I took the cylinder out of the lock because it is a pretty solid lock and I didn’t want to lose or have to drill it if I fucked up.
Still couldn’t get any joy so – when all else fails – more lubrication.
While I was working the lube into the cylinder with the key the core started to come out – a gutting was now happening.
It is a six pin cylinder but only five pins in it.
The first thing that I noticed was (I suppose, in an effort to save money) there was NO circlip. The end of the cylinder is just peened over in one place to fit (not very well) into the grove in the back of the plug. See photo.
After that that I noticed that ALL driver pins are spools. I always thought that at least one driver had to be a regular pin.
The next thing is that all the driver (spools) are the same length.
On closer inspection, on two of the spools (1 & 5 in photo), the narrow section is quite a bit smaller than the other three. This is probably what locked the up pins and prevented any counter rotation a la regular spools. Plus the fact that all the driver pins are quite short.
All in all, I’m glad I gutted it because close inspection explained a lot about this cylinder.
Definitely one of Masters more secure cylinders.
Now I have a request.
Can someone send me a replacement cylinder for this lock. I’ll pay all expenses. The cylinder does not have to be a Master, as long as it fits and has the right cam in the end. It's a really solid lock and I'd like to use it.
If you can help me out please PM me.
Thanks.
Click to enlarge.
The peened section.
For every expert there is an equal and opposite expert.