Hello all, my sons ics m4 was to hot last time he had it checked at our local site, tech there put a spring in it just to get him through the day and advised a m90, I have changed the spring now to the m90, pretty much painless operation but when I fire the gun the power is so low and fires multiple bb's in semi auto also sometimes the bb just drops out the end.... Any help would be much apreciated.
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