I bought an barrel adapter from a company called Tacticool22 here in Walterville Oregon. They sold the item to be used on a 7.62x39 barrel. Problem is the the inside of the adapter is 3mm smaller then the barrel. I checked on three similar firearms and they are the same internal barrel size the adapter was not. The people seemed nice that worked there they responded fast, have yet to here back on my concern. And looks like their policy is I pay return shipping. I am writing this not to bash the company but to give a reminder if ordering from these guys or from any other company that sells barrel adapters, flash hiders or muzzle breaks do yourself a favor and check the specs with a micrometer. The fit was good as I gave them exact external measurements. They did not ask for internal measurements nor did I think that was needed as min specs should have been fine,however it was way to small to be safe. Use caution sure they are an fine company but this was a concern.