"There is no reason why practical rifle cannot be carried out with bolt action rifles or using small-bore semi-autos"
Robert, unfortunately it is obvious that you don't know too much about the Practical Disciplines. Whilst I always respect your point of view, I have to point out that the entire principle of Practical Shooting is based upon Accuracy, Power and Speed. Hence motto of the International Practical Shooting Confederation (IPSC) : - Diligentia, Vis, Celeritas (DVC)
There is a formula (happily done quickly by a computer programme), where your target points scored is divided, or multiplied, or whatever, by the time taken to shoot the course of fire, with the power factor of the calibre being used. This calculation provides each competitor with a number of stage points (usually approx 18 x stages shot in a whole match over a couple of days) and it is the accumulation of stage points which will determine the winner.
So, as you can see, using a bolt action rifle simply will not cut the mustard in terms of speed. Likewise, multiple shot shotguns are used in Practical Shotgun, and semi auto pistols are mostly used in Practical Pistol, although there is also a Revolver Division within each match, for those who prefer to master the old wheel gun.
You are right that a short form of Practical Rifle does still exist in UK, I think referred to as Mini Rifle, using semi auto Rimfire, but naturally due to the lack of power it does restrict the types and distances of targets being shot. As you say, better than nothing, but part of the enjoyment to me is trying to obtain the skill to accurately control the larger calibre's.
I don't see what is wrong with that, and I say again that it appears to be acceptable in every country in Europe, apart from mainland UK. Why is it that just we are considered untrustworthy?
Also, your comment regarding the conversion of semi auto to full auto is a bit of a red herring . . . . . . what is it that people don't understand, that the criminal community can and do obtain full auto weapons anyway !!!