Originally Posted by ShootnMathews
I read that several times and tried that. My personal experience with my first go around with bergers is I could not get my gun to group under 3/4" jumping them. So I decided to try the .010 jam it suggests. Instant 1 hole groups. And jamming it only .010" in my rifle they still extract fine if I don't fire. I even measured it after extracting it multiple times and the length didn't grow at all.
Now my barrel is factory and new. Maybe after it gets broke in better it will jump them better.
During development for a hunting gun I usually start at .020" jump and increase to .080" after pressure checks. On my Savage it was shooting over 1" at 100 yards. The rounds were loaded up during one of my classes. The last three shots were .005" jam with no loaded round extraction issues. Good results. Charge changes and shot again. Best looking results were loaded with 10 rounds and two five shot stings were shot letting the barrel cool during and between strings. Good results and acceptable ES for the 10 rounds. Not it was off to 300 to start drop charts.
One interesting aspect, this was all accomplished during barrel break in. What I noticed was the first two rounds on a clean barrel appeared to walk. Nothing new for some guns. Extra rounds on a medium load were loaded just to "foul" the gun on a clean bore before shooting for development. I rechecked .020" and .060" jump just to make certain the barrel break in and 3 foul rounds needed was not the issue during initial development. Same results, well over 1" at 100.
With my current loads, three rounds need to be fired on a clean bore before the group settles in. The first round will be over 1" at 100, second about half and third half again. Fourth round on all group. I only clean my guns when necessary or at the end of the hunting season. Otherwise they are sitting in the cabinet with a foul bore waiting for the next time for a trip to the range.