UK process for acquiring a firearm, from what I remember, it was a while ago, and I since gave it up:

• Build a 6-12 month "history" showing how/why you wish to use the firearm you propose to acquire. This 9/10 means joining a "Home Office Approved" shooting club where you follow the club's "probationary" training (clubs must legally have probationary training as one of the conditions of their own certification which is its own thing with loads of additional rules).
• Prepare your application. The application will require: a reference from a committee member of the shooting club and a non-shooter reference (priest, community member, local council councillor, etc). They may also seek a reference from your GP (which IMO is a bit silly as most GPs don't really have a clue what this is all about and don't know you personally at all, it's a relic really). The application will also ask you exactly what type of firearm you wish to acquire, where you will shoot it, where will you store it (which must be in an "approved" gun locker), where they keys to said locker will be stored and how you will ensure nobody else gains access to the keys (fun fact: even in cases where husband and wife both possess firearms certificates, you are still not legally permitted to have access to your spouse's firearms – police have asked spouses how they intend to keep their keys hidden from each other!)
• Interview with the certificating police officer. They'll want to come to your house and basically "feel you out". They ask a few questions just to sort of get to know you, they'll ask who else lives in the house, if there are people coming and going etc. They'll ask you to basically repeat some of the stuff you've stated in your application, where you'll keep the firearm etc. If the gun locker is in your house, they'll inspect it.
• They'll mull it over for an additional few months (honestly this is more just because they're slow and understaffed). If the investigating officer is conviced to award the cert he has to take your application to his (or her) boss to get it signed. The head of the local police force will then review the application with the input from the investigating officer ask any questions (my application was nearly turned down at this point but apparently the officer did argue my case and it went through). The bigwig signs your application and they send it to you.
• Congratulations you now have permission to acquire exactly the firearm(s) you applied for AND NO OTHERS. (Even if you buy a firearm and then decide to trade it for another, you cannot – you have to apply for a "variation" to change to a different s/n).

It's long.