SACair Forum

I have an m15a4 spc with all stock internals and have used it in caouple of 8hour games, but never had any problems until a week ago thehop up started sendingrounds about 80 to 100 feet then droped them straight down. before this happened, i did open the gun up for cleaning and lubing since the games were in agressive and dusty terrain. it chronoed at about 360 to 370. (when i bought it it was at 400 to 420) im i did remove the hopup to check the barrel since i had to run through a swamp and wanted check for moister in the gearbox. there was none. just getting into upper end AEGs so it may be somthing pretty basic, but im pretty sure it's not shimmings... but idk. thanx if you can help

Change the Oring for the piston head. Check your air compression. If you don't already know the size for the piston head's oring is 14. You can get them at HomeDepot. Also, you should check your chamber and barrel if they are air sealed. Other than that you might need a new spring because old spring can lose power.

Also check your hop-up spring to see if it is pressing the hop unit back against the nozzle correctly. You can add an o-ring to the outside of your inner barrel to 'shim' it back against the nozzle firmly.