sniper rifles again (promised myself after seeing that post I would never make a mistake like that - -_- )
Ok so we have established he will spend on items that need replacing.
so cylinder heads will need replacing after one or two games? He will also be cashing out and upgrading. Would you say the A&K is better OOTB than the G SPEC. Also, scopes? any ideas on them? i have no knowledge and so can't help him at all in this area
For the VSR Gspec or Pro you will need to replace the piston and sears. Replace those parts will a steel catch piston and a steel sear set. This will give you great reliability ~M120 spring. To do this you will need a new cylinder and cylinder head since marui have started crimping them meaning they will be destroyed if removed.
The gun will last decently stock,my sears and piston shit themselves at ~10,000 rounds but I think mine MAY have been a lemon,but that said the 45* mech design is already not great for high power let alone pot metal sears and a plastic piston.
Another option is to move to a 90* degree system which will be 100% reliable over an M150. Pricey option but you can save money by buying small custom made triggers like the S trigger. You can even use a lathe to get the stock piston to a 90* catch,a few people on AirsoftSniperForum have done this and have been running them on powerful springs with no failure.
A&K M24 comes with a steel Cylinder,Aluminium piston,90* trigger system with steel sears. Compatibility-Trigger most likely VSR and piston/cylinder may be VSR or APS Type 96. Gun is a PITA to take apart due to loctite spam. Otherwise cylinder has a great air seal and the gun has amazing stock reliability. Downside is the hop up unit and mounting blok is different but the hop up takes VSR internals(Hop up arm,feed system,rubber,barrel,etc...)
Scopes- Any 3-9x40 or less even,4x is grand most of the time will do. Most are made by the same few Chinese OEMs. I;ve had great luck with ASG strike scopes