Curing an addiction to one drug with uncontrolled use of another addictive drug isn't necessarily a good idea and there are plenty of accounts of opiate addicts relapsing because of kratom use.
He claims that 300 people are shot per year in the UK...I think he's taking the number of people actually shot in the UK per year and multiplying it by the difference in population between the UK and the USA. Or (more likely in my opinion) someone else did that and he's misunderstood the figure and never bothered checking.

I'm not backing this guy up or anything but I'm also not sure what you're trying to say here. I get the impression that you think it's higher than 300/year?
