I've bought from sportsmansguide, but not the other two. I selected "other." I've bought a fair amount from MidwayUSA and Natchez Shooter's Supply, and lesser amounts from other online suppliers. For 7.62x39 there is probably no good, single, consistently reliable, online source. I don't buy it, but understand the current situation. I do buy .223, and while the current situation not as bad as for 7.62x39, I do have to shop around, and keep my eyes open, for available supplies at decent prices.