Re: necking up remington 7BR case or lapua 6br case which one
Hi i have gont through the process of necking various cases to form 338 Whisper type calibres and am going with a diferent case to try another approach. The Lapua cases are awsome and as stated neck them to 30 cal first then neck them to 338 anneal after fireforming. The cases neck up beautifuly and there is no trouble. The one thing you must watch with either is because you are necking the case up so far the neck gets longer than it used to be and the shoulder part is formed into the bottom 1/3 of the neck. If you have a good close fitting chamber you should neck turn the cases as their is a bulge of thick brass there. Just skim the neck so you keep the original brass thickness at the top of the neck and bring the neck down to a consistant thickness. I have not necked up Rem 7mm Cases but i believe they would have the same problems. You only have to neck turn a case once so it is worth the effort. Also make sure the Lapua cases fit the chamber the Rem cases are smaller than the Lapua cases in the web area. This also means if the Lapua cases fit the Rem cases will be small in the web and that will increase the chance that the head will expand with warm loads and the primers pockets will open and loosen earlier with the Rem case.