what is this part ??

I will post a pic as soon as I download pics from camera. I got a ca g36 when I went to shoot it it double feeds tried all mags did the same thing. Single load works fine one bb at a time by hand. Took the mag holder off and a small plastic piece feel out. It dont look like it was broke off just came out from somewhere in the hop up maybe the hop up adjuster is very loose the piece has 3 flat sides and 1 side is half moon shaped. 1 side is longer like a small tab looks like a keeper of some kind. I am new to airsoft and this is my first gun need to fix before next weekend so I can go to wilcox. Any help would be great. I found this part# on a blowup looks like my part tried to look up with no luck. G36200319P-F [img][/img][img][/img]

I pulled the barrel and the part fits into the hop up but the part just falls out. No other parts were loose in the gun when I took it apart and nothing looks broke. Just not shooting right to many bbs are trying to go into the chamber at once it looks like to me but what do I know I am a new guy to airsoft. Need some info thank you.