I have recently purchased this gun, amazing build quality as usual from a vfc product, just wondering if any of you long term airsofters out there have any recommendations of upgrades that should be carried out? gun is currently only shooting 315-320 fps and my site limit is 350 fps, how would I go about getting up to that level or is it not worth worrying about. gun is completely stock at the minute, apart from the attachments and does shoot amazing and have a good range but as always I would like a bit more If possible.