Thread: Trying something, Eric Cortina method of load development

Originally Posted by Moa Hunter

Just go out in a paddock and run them all through the chamber a couple of times, that will cure them if close to chambering. Fire any that are too tight.
The donut ring on the neck and a normal load method gives a much more consistent fire form case than a soft load.

nah, I'll just pull them and re size them, not wasting 40 primers, projectiles and the powder when I can easily fix it and reuse all the components.

to clarify the fire forming loads weren't soft they were just middle of the road loads from ADI load data, where as the charge ladder was from middle of the road to just above book max.

Originally Posted by dannyb

nah, I'll just pull them and re size them, not wasting 40 primers, projectiles and the powder when I can easily fix it and reuse all the components.

to clarify the fire forming loads weren't soft they were just middle of the road loads from ADI load data, where as the charge ladder was from middle of the road to just above book max.

How do you know 40 wont chamber and eject and not just one or two ? I run all my Ackley reloads through the chamber to check em and some batches get a few tight ones that resize themselves when chambered. At home you can bang the bolt down with your palm - something you dont want to do in the field.

Originally Posted by Moa Hunter

How do you know 40 wont chamber and eject and not just one or two ? I run all my Ackley reloads through the chamber to check em and some batches get a few tight ones that resize themselves when chambered. At home you can bang the bolt down with your palm - something you dont want to do in the field.

40 was the amount of loaded rounds I checked in the rifle chamber at home (after my mate made the comment about some being hard to chamber) where I felt resistance before the bolt was all the way closed, I'm confident they would all chamber just they require a bit of effort to do so (as stated my mate chambered and shot them successfully), Are you saying that I can use the chamber to bump the shoulder back ? Some where not as bad as others but I would have thought that forcing the bolt down to bump the shoulder back would still not result in a round that chambers smoothly (ie:with just the smallest amount of resistance).
I still feel this is not a good idea as bumping the shoulder back after seating the projectile would move the projectile in relation to the lands ?
Anyone else got any thoughts on this before I pull 40 rounds and go through all the effort of salvaging the powder, depriming, resizing, re primimg, recharging and then re seating ?

Na your buggered if you can't get a body bump die.
Get a set of redding comp shell holders as the only accurate way to set your cartridge headspace when sizing.
There is a great podcast from the redding vice president explaining why.
They are not cheap but neither is wrecking your brass.

Sent from my SM-A226B using Tapatalk

I agree by chambering round a couple of times you will move case size by the infintisimal amount needed and it will go in fine afterwards..we did this with the troublesome loads in the BLR .

Originally Posted by dannyb

40 was the amount of loaded rounds I checked in the rifle chamber at home (after my mate made the comment about some being hard to chamber) where I felt resistance before the bolt was all the way closed, I'm confident they would all chamber just they require a bit of effort to do so (as stated my mate chambered and shot them successfully), Are you saying that I can use the chamber to bump the shoulder back ? Some where not as bad as others but I would have thought that forcing the bolt down to bump the shoulder back would still not result in a round that chambers smoothly (ie:with just the smallest amount of resistance).
I still feel this is not a good idea as bumping the shoulder back after seating the projectile would move the projectile in relation to the lands ?
Anyone else got any thoughts on this before I pull 40 rounds and go through all the effort of salvaging the powder, depriming, resizing, re primimg, recharging and then re seating ?

1) Because Ackley rounds dont stretch we want to keep them tight and not size them down each firing so as to extend case life. 2) What I find is that different brands of brass, number of times fired etc causes different spring back of sized cases so it is normal to get a few tight ones. I leave my die permanently set and dont check it for each lot of cases. This means I can end up with a few tight ones sometimes.
If they are all run through the gun pre hunting that seems to fix them as it is normally just the neck junction that is tight.

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

just go shoot sumfin will ya bud....

Originally Posted by Micky Duck

just go shoot sumfin will ya bud....

'tis the plan

So with this rifle soon on it's way back into my hands after a wee holiday with 2 other forum members, I have been pondering what to load for it. I feel like a new round of load development will give me time to get comfortable shooting an ultralight again and well cause what the heck
Last year during the roar/rutt I used some factory sako blade (copper) in my rem mag, it proved to be both accurate and killed excellent.
So I picked up a packet of projectiles to try in the ol Dirty Ackley for shits and gigs.
Will have a look over this thread to refresh my memory of the learnings I had building and developing a load for this rifle.
I'm hoping to achieve an accurate load around 2900-3000 fps but I guess we'll see what it does, if not I can fall back on the ELDM's that I know it will shoot.