There are lots of variables causing AEGs low FPS issues. The air seal is a key point! The hop-up spring, though small, accomplishes big as it can pushes the hop up chamber back into the air nozzle to reach a good air seal. When the hop up spring is not strong enough or too short, or you lost it when you rebuild your AEGs, the hop up unit would moves back and forth, so it doesn’t always line up with the magazine, with the hop up moving it may cause loss of air seal, causing lower muzzle velocity.

Whether you guys have ever used Hop Up Chamber for M4/M16 series from Modify Tech? We released the Accurate Metal Hop Up Chamber for AK47 series officially today. We continue concept of version 2: Redesigned pressure plate makes accurate adjustment easier. The dial and lever are key feature of it.

MODIFY also announced their exclusive distributor in The Netherlands:

Hello guys, we have an exclusive distributor COM-BAT AIRSOFT in the Netherlands. If you have any questions, please do not hesitate to contact them. They would be happy to serve you!