Excellent 9mm ar spring - Angstadt Arms AR-15 9mm 5.4 oz Carbine Buffer Assembly w/ Carbine Buffer Spring, 9mm Buffer Spacer

I was initially concerned about a proper functioning recoil spring for an AR 9mm with a blowback system. I originally looked at a standard AR spring, separate heavy buffer, and a spikes tactical spacer. Fortunately though, this offers all three in one package. As for function, I have had zero issues running my AR 9mm.