Fireforming to Ackley

[quartermaster]

I have fireformed 26-06 cases to 25-06 Ackley before. I found the case length shortened more than my liking, but can’t remember how much shorter the neck was.
I’m thinking of doing a 7mm-08 AI. Just wondering if someone could give me an idea of approximately how much shorter the neck would be. I’m thinking I may be opening myself up to creating a carbon ring. I’m sure it would take quite a few firings, being a 40 degree shoulder to lengthen the neck where it should be.
What I ended up doing with the 25-06 Ackley was to form the case out of .280 remington. It took a few steps, but worked well.
Thanks in advance,
QM

 

[Webster]

I have fireformed 26-06 cases to 25-06 Ackley before. I found the case length shortened more than my liking, but can’t remember how much shorter the neck was.
I’m thinking of doing a 7mm-08 AI. Just wondering if someone could give me an idea of approximately how much shorter the neck would be. I’m thinking I may be opening myself up to creating a carbon ring. I’m sure it would take quite a few firings, being a 40 degree shoulder to lengthen the neck where it should be.
What I ended up doing with the 25-06 Ackley was to form the case out of .280 remington. It took a few steps, but worked well.
Thanks in advance,
QM

I don't know if I would worry about it. If the neck is longer wouldn't the carbon just form a little farther forward.

 

[quartermaster]

I would think that the closer one gets to the end of the chamber, the more would go down the barrel. Not sure. You may be correct

 

[varmintshooter]

In my 223 AI the case gets about .010" shorter maybe a little more.

 

[Walt Krafft]

If you maintain the length you get after fire forming, the carbon ring wont get in the way. IMO the carbon ring only causes problems when people let the cases grow to the point they cover the ring that formed in front of shorter cases.

 

[std7mag]

My 7mm-08AI case length is 2.028".
This is with 2 loadings.
First from standard 7mm-08 to 7mm-08AI fireforming.
Then I shot one 600 yard F-Open match.

I have the PT&G reamer. 7mm-08 IMP 40° with 0.060" freebore.

COAL with the 140gr Berger VLD is 2.898".
2.895" for the 140gr NBT.

I check trim with a Lee case length gauge every reload.
Typically about the 4th to 5th load the trimmer will start to take some off. Not a lot, but some.

After that it will continue to remove some brass with every reload. Again, not a lot. But it does still grow.

 

[quartermaster]

If you maintain the length you get after fire forming, the carbon ring wont get in the way. IMO the carbon ring only causes problems when people let the cases grow to the point they cover the ring that formed in front of shorter cases.

I agree Walt, but I would like to see the necks where they should be. If I were to keep them the same length, then there would be that much more carbon that would eventually have to be removed. I do borescope now and then on all my rifles to get carbon out. I have a decent procedure to do it, but if it gets bad, it’s a lot of work.
I do understand what you are saying.

 

[quartermaster]

My 7mm-08AI case length is 2.028".
This is with 2 loadings.
First from standard 7mm-08 to 7mm-08AI fireforming.
Then I shot one 600 yard F-Open match.

I have the PT&G reamer. 7mm-08 IMP 40° with 0.060" freebore.

COAL with the 140gr Berger VLD is 2.898".
2.895" for the 140gr NBT.

I check trim with a Lee case length gauge every reload.
Typically about the 4th to 5th load the trimmer will start to take some off. Not a lot, but some.

After that it will continue to remove some brass with every reload. Again, not a lot. But it does still grow.

Do you know what the case length was before firing. SAMMI says 2.035 on an 7-08. Naturally new brass is always shorter in this day and age.
How do you like the AI. What velocity are you getting with the 140’s?
Curious how much case length you gain with each firing.

 

[Webster]

I have fireformed 26-06 cases to 25-06 Ackley before. I found the case length shortened more than my liking, but can’t remember how much shorter the neck was.
I’m thinking of doing a 7mm-08 AI. Just wondering if someone could give me an idea of approximately how much shorter the neck would be. I’m thinking I may be opening myself up to creating a carbon ring. I’m sure it would take quite a few firings, being a 40 degree shoulder to lengthen the neck where it should be.
What I ended up doing with the 25-06 Ackley was to form the case out of .280 remington. It took a few steps, but worked well.
Thanks in advance,
QM

The OAL will grow 1-2 thou after each firing. Will this take care of it?

 

[quartermaster]

The OAL will grow 1-2 thou after each firing. Will this take care of it?

I have my doubts. I guess it depends on how short the new brass I get is.
My 25-06 to Ackley was at least 15 years ago. Wish I could remember what I lost in length. It was a lot.

 

[Webster]

I have my doubts. I guess it depends on how short the new brass I get is.
My 25-06 to Ackley was at least 15 years ago. Wish I could remember what I lost in length. It was a lot.

What's the fascination with Ackley cartridges. Your just making things difficult for a small increase in FPS.

 

[Webster]

I have fireformed 26-06 cases to 25-06 Ackley before. I found the case length shortened more than my liking, but can’t remember how much shorter the neck was.
I’m thinking of doing a 7mm-08 AI. Just wondering if someone could give me an idea of approximately how much shorter the neck would be. I’m thinking I may be opening myself up to creating a carbon ring. I’m sure it would take quite a few firings, being a 40 degree shoulder to lengthen the neck where it should be.
What I ended up doing with the 25-06 Ackley was to form the case out of .280 remington. It took a few steps, but worked well.
Thanks in advance,
QM

The website describes many Ackley cartriges. Some have a much bigger increase than others in FPS.

 

[quartermaster]

What's the fascination with Ackley cartridges. Your just making things difficult for a small increase in FPS.

No fasination. Just wanted to do something a bit different.

 

[Curmudgeon]

If all that changes is the shoulder angle how does the neck length change?

 

[L.Sherm]

I fireform many AI cartridges there is no set rule on how much they shorten depends on how much your pushing the shoulder forward and how soft the brass is your using.
As far as the carbon ring goes if you never let one develope you'll never have to worry about it, ive ran stuff .020 short of max length with zero problems.

 

[L.Sherm]

If all that changes is the shoulder angle how does the neck length change?

The neck length doesn't the OAL does

 

[SeabeeKen]

I have fireformed 26-06 cases to 25-06 Ackley before. I found the case length shortened more than my liking, but can’t remember how much shorter the neck was.
I’m thinking of doing a 7mm-08 AI. Just wondering if someone could give me an idea of approximately how much shorter the neck would be. I’m thinking I may be opening myself up to creating a carbon ring. I’m sure it would take quite a few firings, being a 40 degree shoulder to lengthen the neck where it should be.
What I ended up doing with the 25-06 Ackley was to form the case out of .280 remington. It took a few steps, but worked well.
Thanks in advance,
QM

The five or so ai i have all change .015 or so.
I havent ever trimmed but maybe 2 cases. The 40° shoulder slows the case stretch quite a bit IME.
Most of my non ai cases, i let grow to .005 under chamber length and carbon rings aren't an issue.
I always square up the case mouths in my trimmer since they don't stretch evenly

If all that changes is the shoulder angle how does the neck length change?

When the case expands to fill the chamber it draws brass back from the neck. This is the path of least resistance.

 

[L.Sherm]

hat's the fascination with Ackley cartridges. Your just making things difficult for a small increase in FPS.

Whats difficult about a AI cartridge?
How many have you played with?
2 examples i can give you are 3-280-280AI i loaded for gained 240FPS and tge 20VT to 20SCC( 20VTAI ) gained 220FPS.
My 20BRA gained 120 over 20BR i guess this target at 665 fireforming brass was difficult.

 

[Webster]

No fasination. Just wanted to do something a bit different.

Have fun. I'm a varmint hunter. I always picked calibers based based on accuracy. I have a 6BR and a 6BRX. Both can shoot under .400" groups. I don't really get a kick out of owning rifles. I enjoy getting out in the fields where it's quiet and peaceful until I pull the trigger.

 

[L.Sherm]

Have fun. I'm a varmint hunter. I always picked calibers based based on accuracy. I have a 6BR and a 6BRX. Both can shoot under .400" groups. I don't really get a kick out of owning rifles. I enjoy getting out in the fields where it's quiet and peaceful until I pull the trigger.

Can your 6BR or 6BRX shoot like that 20BRA fireforming BR brass at 665, that's just working up a load just like any other no different than any other cartridge.