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[Someshot]

Firstly I apologise if this post is in the wrong section.

Secondly i'll give some background before addressing my issue.
I bought my A.P.S EBB M4a1 over a year ago, and it has never once performed to the standard i'd like it to, it's had average days at best. I had it chrono'd a few weeks back when I visited a new site and it was shooting around 200fps, bear in mind it was sold to me claiming 328. I took it to my local airsoft shop where they said they'd get the fps up to between 300-350 (the fps limit at the site I go to is 350 as it is CQB), when I picked the gun up the guy, seeming quite puzzled, began asking me if i'd changed the hop-up unit at all, when I told him that I hadn't he explained to me that he was confused as to why it had a plastic Guarder hop-up unit in it which he claims is not what it would have been manufactured with and is the source of my fps trouble. After this I skirmished it and noticed just how poor the hop-up is, I don't know whether that's because of the hop unit or any other parts as i'm fairly ignorant of how AEG's work, but I did find that adjusting the hop-up seemed to have no affect. The guy in the shop suggested he ordered in a metal G&P Hop unit and he install that for me.
My question (At last I know) is whether this may genuinely fix my problems or it's just another excuse for me to spend horrific amounts of money trying to get my gun to a passable standard.

Any information would be great, thankyou.