The SAS had a fully auto variant. And one that was a bit shorter. I think even 22 reg kept to semi-auto though. You can get more accurate rounds down range, they've always been the same. Hooligans!
I saw plenty of SLR's tampered with in the armories, trigger sears filed down to make them full auto (I even seen elastic bands and bits of string being used to modify the sear). They were a heap of cack though, they jammed every five minutes. Still I'd rather carry one of them into battle as apposed to the SA80, even the latest models.
Speaking of 7.62. We once had a demo with the Gimpy with regards to PIRA members hiding behind chimney stacks in NI. It knocked the Chimney block off and demolished half of the roof. GPMG, a cracking weapon.