Hello there ok had a bloody good day yesterday at Hunting Grounds perfect weather and cracking people,the drum mag worked spot on for me I tried it in the mag well of several M4 types but it only fitted G&G.G&P and my Krytac so far.The only time I noticed a whinding noise was when it was almost empty and the beast wanted more BBs,needless to say I was well chuffed with the feeding from this mag and had a good amount of interest in it by other players just remember I used 7.4 deans lipo so on a higher fire rate I personally dont know how it would perform.
If I can help you in any way contact me