SMK went through a phase of supplying rifles around the 13-14lbft limit, and disgruntled RFDs sending them back. I keep my rifle at the high tens and my pistol the low fives with heavy pellets.
People don't realise the seriousness of powering up an air weapon into a firearm, or other items classed as firearms. We used to get a lot of Poles, otherwise decent, law abiding folk, but they'd have a Taser because it was legal in Poland, didn't realise with was a firearm here. They'd almost always cry as they were sentenced to the (almost) inevitable five years, waving at their stunned wives and kids. Welcome to England!