.All blocks are machined from 6061 aluminum

.1/2" thick aluminum

.Holes are flat at the bottom

.Below is a short list of calibers that will fit

.38 special

.38 super

.357 sig

.357 mag

.40 s&w

.10mm auto

.22 ppc

.224 weatherby

.6mm ppc

.6.8 spc

.32-20 winchester

.7.62x39