I have had half a dozen orders from Sarco in the last year; all shipped quickly and the items were as advertised. In several instances, the items were advertised as used but were actually NOS unused/unissued and original.
I would have no qualms about ordering from them.
I also deal with Numrich [Gun Parts Corp] and am waiting for a small order today. They also ship quickly and most parts are acceptable, with the exception of a sear spring for my C96 Mauser that was either inferior steel or not hardened. Coat hanger steel most likely - Chinese/Pakastani???
In event event, I order from both of them regularly. AAA+++