Fire form question

[bobcat93]

Say I need to fire form from 223 rem to 223 rem improved..and not something that needs a fales shoulder for a drastic change in case dimensions..
Is there a reason I would not want to use my favorite 223 load..
I've read to use a mid level powder charge for fire forming and was curious to why?.. then I was reading by using a hot load you can stretch primer pockets during fire forming..is this so..
Please fill me in.
Thanks

 

[martin22250]

Say I need to fire form from 223 rem to 223 rem improved..and not something that needs a fales shoulder for a drastic change in case dimensions..
Is there a reason I would not want to use my favorite 223 load..
I've read to use a mid level powder charge for fire forming and was curious to why?.. then I was reading by using a hot load you can stretch primer pockets during fire forming..is this so..
Please fill me in.
Thanks

I would use a normal load with the bullet hard in the lands and a very very light film of gun oil on the case. One shot and they are good to go.
Dustin

 

[XBBR Shooter]

Say I need to fire form from 223 rem to 223 rem improved..and not something that needs a fales shoulder for a drastic change in case dimensions..
Is there a reason I would not want to use my favorite 223 load..
I've read to use a mid level powder charge for fire forming and was curious to why?.. then I was reading by using a hot load you can stretch primer pockets during fire forming..is this so..
Please fill me in.
Thanks

Normal advice for forming an improved case is to use a max load of the standard case. Light oil on the case before firing insures no stretching. I have a Lyman case lube pad that is specially set up for this, soaked with G-96 oil.

 

[Geno C]

A properly set up Ackely improved chamber should require neither jamming a bullet nor oil in the chamber. With the case supported fit from the base to the neck/shoulder junction, the case can't stretch length wise olny expand around its circumference to fit the chamber walls.
My most recent AI is a 223 and it is set .007" short of zero head for a standard 223. There is no measurable case stretch on fired cases.

 

[XBBR Shooter]

A properly set up Ackely improved chamber should require neither jamming a bullet nor oil in the chamber. With the case supported fit from the base to the neck/shoulder junction, the case can't stretch length wise olny expand around its circumference to fit the chamber walls.
My most recent AI is a 223 and it is set .007" short of zero head for a standard 223. There is no measurable case stretch on fired cases.

Most Ackleys have excessive case stretch problems... many suffer head separations often.
And 0.007" is not enough crush to insure proper forming.
New case headspace allows 0.010" variance - so with your 0.007", a new case can still be 0.003" loose.
And, a properly formed Ackley case from a well made chamber should shrink a fair amount... 5 to 10 thou.

If your cases are not shorter when they come out, than they were when they went in, then your cases are stretching at the web.

 

[Geno C]

Saami base to neck/shoulder junction is 1.5573-1.5519"; so not .010" variation. My reamer is 1.5497" at the same spot and it is actually .003" short of that for good measure. Getting your chamber done to your specs and good communication with your smith about what you want is critical in getting the results you want. The results I want are an improved chamber that I can load any factory ammo if I had to and come out with a formed case and no stretch. Ymmv

 

[XBBR Shooter]

Saami base to neck/shoulder junction is 1.5573-1.5519"; so not .010" variation. My reamer is 1.5497" at the same spot and it is actually .003" of that for good measure. Getting your chamber done to your specs and good communication with your smith about what you want is critical in getting the results you want. The results I want are an improved chamber that I can load any factory ammo if I had to and come out with a formed case and no stretch. Ymmv

It is not what it says on the reamer print - it is how far the smith runs the reamer in the barrel... what is the actual measurement to that point on a fired case.

 

[Geno C]

It is not what it says on the reamer print - it is how far the smith runs the reamer in the barrel... what is the actual measurement to that point on a fired case.

Exactly! That's why I said good comms with your smith are important. I said I wanted mine .007" short of a rem223 go gauge: .003" short of the 223ai go gauge.

 

[mikecr]

Say I need to fire form from 223 rem to 223 rem improved

What is the improvement(whats changing)?

 

[Phil]

What is the improvement(whats changing)?

40 degree shoulder and straightened case walls, somewhere around 5-7% case capacity increase......

 

[Deleted old_dood]

Say I need to fire form from 223 rem to 223 rem improved..and not something that needs a fales shoulder for a drastic change in case dimensions..
Is there a reason I would not want to use my favorite 223 load..
I've read to use a mid level powder charge for fire forming and was curious to why?.. then I was reading by using a hot load you can stretch primer pockets during fire forming..is this so..
Please fill me in.
Thanks

I've fireformed about 300 cases using a load approaching max but with the bullets jammed about .010. never had a problem with primer pockets. I only used Lapua brass.

 

[mikecr]

40 degree shoulder and straightened case walls, somewhere around 5-7% case capacity increase......

So is this an Ackley improvement (Ackley chamber)?

 

[Phil]

So is this an Ackley improvement (Ackley chamber)?

Yes Sir......

 

[mikecr]

Use your favorite load.
The Ackley standard is easy that way.

 

[bobcat93]

I was just curious about primer pockets stretching..haven't had that problem..and I thought you want a good stout load to force the case to expand properly..
Also I had purchased a lot of 1000 1× fired LC 5.56 brass and had the case separation issue spoken about above..one member said it was probably saw brass..I don't know what that is.. machine gun maybe? ..that is all I used in my rifle the first yr. I shot it..I bought a batch of some new Remington 223 brass.. lightly oiled the cases with kroil when fire forming and didn't have one problem with case head separation..I could see how that issue can turn dangerous in a minute..I've had necks come off in the barrel from that brass..it would be easy to close the bolt on some junk in the chamber and blow the gun up..I inspect everything that goes in that rifle and everything that come out...it's kind of a hassle..once accuracy start to drop I will send it back have the barrel set back and hopefully not have this issue..I'll tell you what..my 223 improved 40 is one accurate machine..it's a shooter so I deal with it..I just read about the primer thing and wanted some feedback..thanks guys
Oh and I jam the bullets a little..

 

[Geno C]

A full power load in a Ackely chamber will make less pressure and velocity that it would in the standard chamber so it shouldn't cause primer pocket problems. Machine gun brass is definately a lot more likely to have head separation. If you can measure the distance from the base to the neck/shoulder junction of virgin and formed brass that should tell you it the chamber has the possibility to stretch brass. Formed should come out shorter than virgin.

I have a 22-250ai that is .040" too deep; .04 not .004! That one needs a solid bullet jam with lots of neck tension or a false shoulder. Needs a little lube on the case also to avoid case stretch. That one is a pain! Shoots good though.

 

[MagnumManiac]

"Most Ackleys have excessive case stretch problems... many suffer head separations often.
And 0.007" is not enough crush to insure proper forming.
New case headspace allows 0.010" variance - so with your 0.007", a new case can still be 0.003" loose.
And, a properly formed Ackley case from a well made chamber should shrink a fair amount... 5 to 10 thou.

If your cases are not shorter when they come out, than they were when they went in, then your cases are stretching at the web."

This statement is so far from the truth. The cases will NEVER lengthen in an improved chamber, even if they ARE stretching at the web. Please explain how it can possibly stay the same or lengthen when it is the top third of the case forming to the chamber? The case would have to be short by the amount it stretched, wouldn't it? HOGWASH! How many improved chamber rifles do you own?
Have never had case stretch problems with a PROPERLY cut chamber with .005"-.008" negative headspace. I form cases from 22-250AI through to 375 Weatherby, 404 Jeffery and 338-416 Rigby Imp none stretch causing head separations. Even belted magnums that headspace on the belt, still come out .020"-.030" short in the neck. The brass has to be pulled from somewhere, and that somewhere is always the thinnest area cause it expands first to fill the chamber and seal it.

I must admit I switched to forming without bullets some time ago, but, I've done my fair share of firing factory ammo in improved chambers without a single hiccup. I still do it if I get given factory ammo somebody no longer needs in a cal I use that is improved.

 

[nvbroncrider]

Ackley's are set up for a crush fit. Headspace on one is -.004" of the parent chambering which if properly done the bolt won't close on the parent go-guage. You do not have to jam them either although it's my preferred method on my 338-06AI is to run around 50-55k and set with a slight jam. I tried both ways I just like to jam just in case I have a piece of brass that's outta spec @ the shoulder. In fact my smith told me if I was in a jam I could run plain old 06 ammo in her might not shoot real good but it would shoot.

My 7 Mashburn uses 300WM as parent can be formed from 300 H&H as well but with 300WM after putting through the FL it's tight going in the chamber fire it off comes out like butter.

 

[Shaggy357]

All of the measurements and tossing of data is worthless to you. Please ignore that unless you have a blue printed action and chamber.

In order to make proper brass for your gun, you need to size cases with the false shoulder to stop the brass stretch, or you need to seat a bullet out far enough to engage the lands. Seating the bullet out to engage the lands with a near max load could cause excessive pressure. For me, the majority of the time, I find putting a false shoulder in the case to be the best method of creating brass, for MY guns. I have lots of dies and take the time to create the correct combination to make that brass fit my chamber for forming. You have to do the same. If the near max load with bullet seated out is your method, I would still back off the load a little to ensure you do not get too much excessive pressure. That would not be good for your brass either.

Again, the SAAMI or other specs and measurements are worthless unless you know EXACTLY what your chamber measurements and bolt fit are.

My $.02 worth.

Steve

 

[shortgrass]

I think most of you guys should bother to read P.O. Ackleys' books ("Handbook For Shooters and Reloaders" , a 2 volume set) instead of getting your information off of the interdnet!