The brass has increased head hardness so it can tolerate higher pressures. Peterson also increased its internal volume slightly so it works better with the slow-burning powders (like RL 26, or H1000) which shooters tend to favour for this round.
Prior to the introduction of Peterson’s .22 Creedmoor, shooters had to take 6mm or 6.5 Creedmoor casings and neck them down to .22. There are a few problems with necking down. When you take a larger calibre with the correct neck wall thickness and neck it down to a smaller calibre, that excess brass bunches up in the neck. It creates a tension band, what some people call a doughnut of brass in the neck, which has a negative effect on loading, bullet release and accuracy.
A trait of cartridge brass is that it work-hardens – which is to say the brass gets harder each time you “work it.” So the effect of necking down a casing which has been properly annealed, is that after you “work” it, it is no longer properly annealed.
Finally, necking a larger calibre into a smaller one results in neck walls that are too thick. The ideal neck wall thickness for a case the size of .22 Creedmoor is .0143 to .0148. Necking down results in neck walls thicker than that. Peterson .22 Creedmoors all fall within that ideal spec.
Peterson Match-Grade Brass rifle casings are manufactured on a new, state-of-the-art case line which uses cutting-edge technology to produce some of the most precise and consistent casings on the market. They are committed to producing Match-Grade Brass that enables shooters to get more reloads per casing than industry average.
Warning: Only use Peterson Cartridge Co. casings in firearms in good condition, designed, marked, and chambered for this cartridge. Do not use Peterson Cartridge Co casings for “fire forming” or any other purpose other than what they were designed and tested for. Peterson retains no responsibility for the enclosed casings if they are used outside of the manufacturer’s recommendations.