I am kind of wary of such things amongst friends. I also don't think that most people posting here did quite understand your question.
If your friend buys the firearm, he has to do it under his name, you are obligated to hand over the money to him before he buys it. He has to treat the firearm as his own and follow the regulations. He must not let you give possession until you have a PAL and he verified your license. Sure, you can go to the range together and you can shoot it under his supervision.
IF the firearm should get banned before you get your PAL, you will legally never be able to take possession, money is gone.
Oh yes, Wendell above gets a clown badge from me.