Lyman Custom Fit Loading Blocks - Lyman Custom Fit Loading Blocks are designed to provide a precise fit for a family of cartridge sizes. Made from tough durable polymer Custom Fit Loading Blocks hold 50 cartridges and will securely nest together for easy storage. They come in 6 sizes to match up with a large variety of cartridges. Each block is clearly marked with the diameter of the cartridge storage hole.0.388 Size Hole Fits: .17 Hornet .17 Rem .17 Rem Fireball .204 Ruger .22 Hornet .222 Rem .222 Rem Mag .223 Rem .30 Carbine .300 AAC .32 ACP .32 H&R .32 S&W .327 Federal