I took apart my VSR to simply change my hop-up bucking, but when trying to screw the outer barrel back into the receiver, it goes smoothly for one or two turns, then just jams. I've tried cleaning out the grooves with a knife, but it still just turns a few times then jams. Does anyone have any...

Basically, I would like to buy an airsoft sniper! There are may sites around where I live and they all have a 450 fps limit for snipers. By the way, I'm in the UK. I have been doing some research and have owned a few cheap guns so I am not a complete noob. I have been looking at the m57 l96...