Hornady AP Powder Measure Kit vs Mark 7 Powder Measure? in non-Dillon Reloading Equipment Posted March 10 Mark 7 has 2 mechanical powder measures that I've seen. Once with a machined body (2 actuating arms on the powder barrel) and one with a cast body (1 actuating arm on the powder barrel). I only have experience with the machined body one with 2 actuating arms. I've had constant issues with the screws on the barrel coming loose even after hand tightening multiple times. I also use one body for 2 drums (pistol & rifle) and have had those custom screws snap right where the thread ends during loosening. Mark 7 replaced one of my drums once and the second time that has happened they told me to purchase a new one so one of my drums only has 1 actuating arm like their cast body version powder measure. I've since ditched their screws, purchased matching thread grade 8 screws from Lowe's and they've been working great without coming loose or snapping.