Thread: Trying something, Eric Cortina method of load development

so bit of an update....it's been a bloody busy weekend trying to make sure I'm organised for a week in the hills at the end of this week......
I took the 30 06ai to the range after disassembling all of my rounds and bumping all the shoulders so they would chamber nicely thinking job done should be ideal now....well I could't have been more wrong....

fired 3 of the bumped re manufactured rounds and whilst they grouped well I was getting hard extraction, having to lift the bolt 2 or 3 times before the chamber would release the case
Didn't have the chrono with me so couldn't check the velocity but assuming that bumping the shoulders back has caused a pressure spike and I am not happy to be shooting a load that is hard to extract.
Went back to the lead shed and loaded a quick ladder of reduced charges and then back out to the range to see what results I got.
started my ladder at 56.5gn and worked up in .5gn increments to 58gn, most shot at or just under and inch with E.S ranging from 40 down to 5fps these were shot over an optical chrono that I have learned whilst it gives consistent results the accuracy can be skewed by light conditions the E.S will be spot on but the actual velocity is often 20-40fps out.
Naturally I went home and reloaded 6 more rounds that produced the 5fps E.S (which consequently shot well under an inch like about .5").
I shot the first 3 rounds with the magneto speed attached to the barrel which predictably created a P.O.I shift but still shot a fantastic group and an E.S of 7fps, I then shot a second group without the magneto speed to confirm grouping and zero which was spot on...bloody lucky it was and I now have another sub MOA load sorted in under a day.
Velocity was lower than my previous load but with the shoulders not bumped enough the rounds were hard to chamber and I have to wonder if I was over pressure and not seeing the signs as the brass was out of spec to begin with, the Ackley certainly is teaching me a fair bit I do prefer to do my load development with a little less time pressure though.
So I ended up pushing the 178gn ELDM's at 2816 fps with a E.S of 7fps over 9 rounds which bodes well. whilst it isn't the 29xxfps I was getting I am more than happy that 2816fps will kill well out to more than far enough away.
I may at some stage do the whole load development again....maybe not it shoots bloody well, but I feel if I had done the seating depth and charge ladder from scratch with the cases sized properly I could squeeze a few more fps out of it....but do I really need it ? in reality probably not.
Will take it hunting end of the week anyway as that's what I built it for.

Strangely the optical chrono and the Magnetospeed read the same in strong bright sunlight conditions