Jeff, you obviously don’t know anything about guns. That switch on the back, while correctly identified as an evil barrel shroud, only has one purpose – to render this rifle undetectable by airport scanners. It is afterall a Glcok.
The switch that makes it go full automatic is the slotted round thing at the top of the wooden forend – the slotted switch on the bottom of the wooden forend is the one that would normally hold the serial number, which as you can see has been filed off. This is clearly a criminal’s gun, as they have even gone so far as to disguise those two switches a slotted screws – only fooling the average person and never a highly-trained officer of the law. I have it on good authority that the Glock 50mmm caliber has no screws, so there’s your answer indeed.
Those mysterious military grooves on the side of the front sight are known to firearms experts as “superposed” and are a hold-over from before the days when all guns were registered. They were made illegal by the gun control act of ’68 which even President Reagan himself said was the greatest legislation ever passed in this country, in part because a superposed military sight only makes rifles like this more deadly. However, when Bush repealed the AWB in 2004, he once again allowed such aweful instruments as this Glock 50mm rifle – complete with the deadly military superposed sights and barrel shroud switch – back on our streets. These guns and their high-capacity banana ammunition have no purpose but to spray fire and no one needs something like this.
I’m guessing that this gun is not registered and as such, the photo is against the law in most jurisdictions.