I just ran into a new (to me) problem at the range today. Using one bullet in particular I got sooty cases at one powder level and when I moved up one grain, the cases came out with a major crush indentation at the shoulder. (Sorry, no pics right now, but the cases are covered with soot almost down to the base and the shoulders are crushed in on one side.
I've been testing loads for the new 257 Wby barrel that I recently installed on my Savage 116. I headspaced it carefully using go/no-go guages, and I ran about 40 bullets through it without trouble earlier this week. Here are the details of what happened today.
I started out loading 100 grain flat base bullets, and ran about 40 bullets though the barrel, using four different powders at various levels. All the brass I've used so far is fresh, unfired factory brass. Since the Wby throat is quite long by design, there's no hope in reaching the lands so I seated the 100s about one bullet diameter into the neck of the casing. All 40 shot great, with several groups well under an inch, and the cases came out clean and showing no signs of pressure.
Today I wanted to start working up loads using the Berger 115 VLDs. I loaded up four different charges of RL25, also into new factory brass. Since Berger recommends seating their bullets touching the lands I seated them as far out as I could. I was still nowhere near the lands (about .030 or more away) but due to this the bullets were less than one diameter into the neck of the case. They seemed secure, no give or wobble in the case neck, so I went to the range. My first two shots at 100 yards were almost touching, and the third not much further away. I was thrilled, but I noticed that the cases were coming out very sooty. No pressure signs, easy extraction, but sooty cases. I cleaned the chamber before the next set, which had one more grain of powder than the first. The first shot of the second set was normal, nothing odd I could notice. It extracted easily, but the case shoulder was crushed in. Puzzled, I decided to clean the barrel and the chamber thoroughly. After that I tried one more shot and the case was damaged/crushed in almost the exact same way, so I bagged it.
I went back to shooting some more loads with the 100grain bullets and shot another 30 rounds before coming home. No soot, no dents, just normal everything, so it's not the gun. Since I was starting out fairly conservative with the Bergers, it's not pressure either. I shot some much hotter loads with the 100gr flat base bullets, no problems.
So why am I getting gas leakage ONLY with the Bergers? I've never heard of or seen this, but maybe some of you have. Could it be the minimal seating depth, or is there something about these sleak boat-tails that's contributing.
My first test will be to drop back down in charge weight some, and then seat the bullets considerably deeper to see if that solves the problem. I'm all ears to hear from some of you though!