EVEN if you can get it in thru the firearm way, you will have another problem. The length of firearm could be too short and considered as a restricted. Then there's the semi automatic ONLY, Finally there will be a list of banned firearm you must follow, which means AK, Mp5, G3 are out of option. Overall it would be quite troublesome, even after custom cause you cant get it fps down that easily.
I know what you thinking, I thought it awhile ago but its not a viable way. And PAL is HARD to get nowadays, and you have a criminal record, you cant get it.