have $300 to spend on just internal upgrades alone. The Airsoft gun I want to upgrade is the CYMA Full Size M14 Airsoft AEG Rifle. My buddy gave me a some scopes that will fit this M14 so I'm not looking for external upgrades right now. I want to have this gun as a outdoors DMR but I find it's lacking in range. Yes, I'm well aware this is a cheap $150 gun so I'm not saying it's a bad gun. I've built a few Airsoft guns before but it's been a long time since I picked this hobby back up. I want to know what's the best spring, gear box, hop up, motor, and barrel, and piston and what ever else I should consider for internal upgrades with a $300 budget? I might even go $350 to $400 if it's worth it. So, keep in my mind I want it to be reliable as well. Thank you!