This is an interesting topic. The industry as a whole has spent a fair amount of effort for a lot of years to polish off the anneal line, and provide bright, shiny brass to the end user.
At some point in time, Laupa entered the fray and chose to leave the anneal line visible on their brass. Lapua is regarded as one of the top brass manufacturers in the world, and the association of a visible anneal line and quality brass quickly became en vogue.
Truth be known, all brass cartridge cases are annealed. They actually are annealed many times throughout the manufacturing process. Something on the order of 12-15 times throughout. The only difference between anneal line and shiny is one more run through polishing to rub off the anneal line.
My long time customers will remember all our early products did show the anneal line, and some still do. But for the most part, all our orders have been switched to polished bright brass. The reasoning for this is mostly function, and somewhat cosmetic. We were running into a problem when seating bullets. After collaborating with ADG and Redding, we learned the anneal line leaves a sticky residue. That particular residue was causing inconsistent seat pressure while seating the bullet.
This doesn't sound like much, but it was creating an issue. The Redding seater die we use for most rounds is the competition die. This die has a floating seat plug, that rides on a cushion of air inside the die. Redding states to not compress powder charges with that die. The result of the anneal line residue was equivalent to a heavily compressed powder charge. The end result was a flared mouth on the seat plug, which caused it to stick inside the die. This was all leading to inconsistencies with seat depth, which caused 20-50% more time to work through each batch that were off a little.
Fast forward to bright brass, and the problem is virtually eliminated. We have since added in a high end case trimmer that trims, chamfers the inside case mouth and de-burrs the outside case mouth all in one step. We have added a run through the trimmer to even up and smooth out the mouths prior to loading. The end result is a more consistent seat depth the first time through the seat die, and at a rate that is much faster than before. This allows us to increase consistency on the product and produce it faster to fill orders. A win win all the way around.
Send us an email or text with any questions you might have about our loading process or any other topics you might be interested in.
North American Ammunition Company