I've been reloading for my 7mm Rem mag for a few years now. I read alot online and there's tons of miss information, so it's very hard to learn. I called Berger bullets and talked to an extremely helpful, and knowledgeable guy there that is on the tech line. He's a few years older than me and started reloading for his dad's 7 mm Rem mag in the late 50's. He's a champion shooter with the owner. He told me how he reloads at target shoots and I was able to get him to educate me enough to know what I needed to know. He told me to bump the shoulder back on fired brass 0.002" He said that's plenty accurate for a hunting rifle. And specifically if you drop a round on the ground or get a bit if dirt you can still cycle the bolt with 0.002" shoulder bump. If you resize to bump the should 0.002" it's not doing much work on the brass. The further back you resize the more you rework the brass and the sooner it will fail. Case hardening is the term. My experience with near full recommended powder charges with 165 accubonds, pretty hot, I started seeing signs of failure at about 5 or so resizings. I annealed the brass and got a few more shots. Annealing is another black hole. The guy at Berger Bullets told me how he does that. I read that guys use a torch with the flame on the shoulder and when the case end is too hot to hold, it's been annealed. I'm an engineer and had to test myself, yes I know. I got temperature paint and painted the shoulders and when the paint melted the case was too hot to hold. LOL..I don't anneal anymore, too much of a hassle and another potential viable in the reloading process.
I fell down the back hole abyss of reloaded and grabbed onto reality before it was too late!! I think!! The guy from Berger Bullets and Nosler both said case length is critical and cases should be within 0.002 of other. If you trim one case and chamfer the case, chamfer them all. Bullet seating depth is critical too, stay within 0.002" Ogive. Those two things are absolutely critical. Same case length within 0.002 and same Ogive within 0.002. Next, if you ultrasonic clean, swab the necks inside with a bit of graphite lube with a lube brush. That's basically it for me. If all things are equal, 3 times loaded shells group as well as first or second fired, so long as case length and ogive are within 0.002" Your mileage my differ. I'm not very anal by nature and resisted reloading as long as I could until I got better and shooting and wanted better results. BRUH!!
I’ve been thinking about trying one of these dies though I haven’t had any issues with my .300wm cases yet. https://www.larrywillis.com/300winmag.html
So yeah, that's where I landed a well. I wish you'd told me this 2 years ago! lol!
If you size it and notice you are about 1 or 2 thous shy of shoulder bump, you can switch shell holders with know distance to simplify the next resizing. I just move my die. It takes 1 or 2 times to get to the exact size. Sometimes I go over a tad, which is where the shell holder variations would be better, as you don't have to guess. It's all personal preference.
