- Mar 30, 2013
I'd be recording the following on fresh cases, fired cases and fired-sized cases.So, I annealed all my brass and went back to the bench to see if I can get the shoulder bumped. I removed the firing pin for the bolt (M700) and chambered a fired, sized case. Stiff bolt closing. I preceded to size another case with shell holder .010, no change. I grabbed another case and tried shell holder .008, no change. I did this all the way to .002 with no discernible change using different brass with each shell holder.
Hornady factory 7x57, fireformed in my rifle with a 40 degree AI chamber. All brass were then loaded again as 7x57AI with RCBS 7x57AI 40 degree die and fired again. That twice fire fired brass was loaded a 3rd time. These are the loads (3rd loading) where I've had 3 that I cannot close the bolt per post #1. If memory serves me right, I've had tight closing bolt with some at after the 2nd firing but nothing near what the 3 were that I had to pull. The remaining 20 loaded rounds I have all chamber nicely with a few that have a little resistance but not bad at all. I started this thread thinking It's a simple shoulder bump issue but I can't seem to figure it out. The rifle has about 100 rounds down it and shoot great. I know I've read where some reamers don't quite match the die and one's 40 degree isn't the others. Thinking the next step is to trim all down to 2.225 which I think is the standard 7x57 trim length. A few I measure last night were at the upper limit of 2.235-2.240. I may have to eat crow from my reply on post #20 of not needing to be trimmed.
Is it possible that my chamber is just too tight? Die is mismatched?
- base to mid-shoulder length measurements
- Web diameter
- Over all case length, I'd trim about .001 under suggested trim to length just to be sure
The web area on the case can cause snugness on close, ran into this on my 6.5 PRC. If you don't have your bump set correctly the cases will sometimes not go into the die the correct distance to resize both the shoulder distance and the web area. I found with my setup I needed to bump this 6.5 PRC .004-.005 to get the whole case properly resized. It cured my web area size issue completely. I went through a bunch of fired cases moving the die down and up until I hit the sweet spot.