I put an M16A1 upper on a carbine stocked lower. Which weight buffer should be right? It used to be a retro M16 build. With the rifle buttstock and buffer, it wouldn't cycle Wolf ammo but did fine with Rem/Fed 223 and 556 m193.

Thanks

There is not really a buffer that will "do fine" with cheaper steel cased ammo. Wolf is really the better of them but still a little under powered especially when compared to 5.56 ammo. If using a carbine stocked lower and you would like to shoot steel cased mostly just use standard carbine buffer and spring. But for your application it sounds like the Vltor A5 System would work great. I have not used it personally but have done a lot of research on it and talked to those who have used it. It has rifle length reliability in basically carbine ( collapsible stock ) configuration. It is a cool balance and something worth looking at.