Gas = More realistic, better trigger response (compared to a stock AEG) sounds better.
Electric = More reliable, no cooldown issues, cheaper running costs, cheaper upgrade options.
You get the idea.
(my opinion anyway..)
Can't purchase the Proballs from Socom because of my old address on my bank info, damn. Will get that sorted, thanks for the input folks.
Tried using the BBKings but I'm pretty sure they've swelled up due to a tiny hole in the packaging did get one or two to feed through my SVD but the rest of them jammed it up.
Been looking around for heavy weight bb's for a few weeks and came across these, can't seem to find a recent review about them.
http://www.patrolbase.co.uk/airsoft-bbs/we-europe-nuprol-0-43g-diamond-grade-6mm-bb-3000-light-yellow.htm#.VpQcafmLQdU
Price is ok, I guess. I've read that ProBall bb's are great, but can't seem to find any that are heavy weight.
Get a Prometheus barrel, you'll gain much more noticeable results combining with your suggestions. Although, you'll probably get better performance replacing all the stock internals with mancraft parts.
This has been answered hundreds of times, you can use them, there is nothing wrong / illegal with you owning RIF's. If you want to purchase RIF's however, you need to be on a database which retailers can check if you're eligible (UKARA)
£50 for a 3D printed KAC silencer, you can get decent ACM ones for under £30..
http://forums.zeroin.co.uk/showthread.php?266739-Barrel-shroud-suppressor-your-14-5-barrel-to-10-CQB-in-seconds