You can drill a backbox lock, but it's not the same as drilling a coin door lock. Rather than drill all the way through, like a coin door lock, you want to drill the tumblers. Use a bit about the size of the key slot. You'll feel each of the tumblers 'give' as the bit cuts through them. Do both sides. Once you think you've drilled enough (you probably haven't), jam a big standard screwdriver in the slot and see if you can turn it. If not, blow out the shavings and drill some more.

It's messy and usually takes a while, but eventually you'll be able to turn the lock. If you have to buy the right size drill bit, buy two as broken bits happen when drilling tumblers.

I drilled a Xenon backbox lock two days ago. Took a while and left a lot of shavings on the floor, but it turned easily with a screwdriver when I was done.

I drilled the backbox lock on a High Speed yesterday. Because it isn't attached to a mechanism, just has a hasp, I was able to quickly drill all the way through it. Didn't have to drill the tumblers. Not sure if all System 11's are the same way, but the lock on High Speed is on top and just behind the backglass.

No matter what quality of drill bit you use, it will get chewed up fast due to the different metals used in the lock. A dull bit will take forever and a new bit will quickly do the job. 1/4" bit to drill all the way through, 1/8" bit to drill the tumblers.

The High Speed was in an exotic/ rare car rental place, right next to the bar. Coolest car in there was a McLaren 600, which you can see the back end of in the pic below. High Speed is behind the Ferrari pool table.

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