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. 0.615 Hole Size Fits : .30-378 Wea. Mag .338 Lapua .338-378 Wea. Mag .348 Win .378 Wea. Mag .40-65 .416 Rigby .416 Wea. Mag .45-100 .45-110 .45-120 .45-70 .45-90 .460 Wea. Mag 7.62x54R