case separation - fireforming

J

jpipes

Guest
All -

I experienced my first case separation today while fireforming brass for my new 223ai. I was told that it's probably not headspace issues, just that the load (55 gr FMJ, behind 26 gr of varget, in virgin winchester brass) might have jumped too far and simulated headspacing issues.

To that point, the fireforming loads with 75 gr amax, loaded as close to the lands as I could get while still feeding from the mag box, turned out fine. There is a slight "ring" in the same place that the other loads broke the case in two.

Attached are pictures of the split cases, along with a piece of brass loaded with the amax bullets.

The rifle specs are as follows: shilen 8 twist in 22inches, fully blueprinted 700 action.

Thoughts?

Best,
Josh
 

Attachments

  • separation.jpg
    separation.jpg
    20 KB · Views: 338
I'd jam 75 Amax's or some other long bullet in the lands to hold the case squarely against the bolt face to eliminate any jump. Glad your not hurt.
 
Sounds to me like the chamber is too deep.
Ackley Imp. chambers should be cut so the virgin brass is a crush fit in the chamber .
 
You have excess headspace.

You cannot fix it by seating your bullets long.

You will need to false-shoulder to fix it.

You will always have excess gapspace.

Your gunsmith screwed up.

al
 
Thanks all. Upon closer inspection of the fired cases that did not separate, about 1/3 rd of them are cracked or otherwise compromised. Frustrating, but surely he'll fix it.
 
Maybe the 'smith did screw up if he didn't use an AI no-go gage, maybe not. I'd also suspect that the new brass might be too short for the chamber, even if the chamber and brass are within specs.
Another example of how one could benefit from a "gizzy" or "chamber seating stub". A short piece of barrel, ends squared off, reamer run in far enough to have most of the shoulder is the description, whatever you want to call it. Trusting chambers, brass and dies is not always wise.
 
Thanks all. Upon closer inspection of the fired cases that did not separate, about 1/3 rd of them are cracked or otherwise compromised. Frustrating, but surely he'll fix it.


Mr. Josh, do you trust and believe in oiled cases while fireforming?

Mr. Josh, do you trust and believe, that this gentleman gunsmith will fix your problem?

Gentleman, would you believe, that there is a reason, why this gentleman gunsmith didn't do the job right.

Con
 
Brings up a question

Something I assumed because my gunsmith always test fires rifles he builds.

Is it common pratice to build rifles and not test fire them?

Thanks
 
If the chamber is too deep then nothing will really fix it for factory ammo except removing the barrel and facing some meat off the barrel shoulder and barrel face.
This is because the Ackley shoulder has to blow forward a long way and it puts a big stretch on the case body if the brass is too hard in the shoulder area. This is in addition to any excess head space. So a tight crush fit on the case is required. Also annealing past the shoulder a small amount helps the shoulder blow out wile reducing the stretch on the case body further down toward the web .
 
All -

Great data, thanks for taking the time. The most perplexing thing is that my smith did test fire for feeding, safety, and function. As a matter of fact, he gave me one of his fireformed rounds, which I have not shot yet. It looked as perfect as can be, without the "ring" mid case length (FC brass, unsure as to the whether or not it was O/F or virgin).

Perhaps my fireforming loads are too hot? I'm talking to my smith tomorrow as I am scared to shoot the darn thing.

Once again, thanks for all of the data.
 
Well
One thing that could cause this is:
IF full length sized your brass prior to fire forming and bumped the shoulder back to far. THat could cause head space issues.
It is not that uncommon.
If you are sizing your brass down to far and then fire forming at the same time it could cause some problems such as you see with your gun.
Ted
 
Well
One thing that could cause this is:

If you are sizing your brass down to far and then fire forming at the same time it could cause some problems such as you see with your gun.
Ted


Gentleman, would you believe, that a properly oiled case won't give you any of these problems.

Con
 
Just shot 15 factory remington 223 55gr through the rifle, and had one separate, and all cases have that light "ring" around the midsection. I've never fireformed before, but I'm assuming that ring ain't normal?

I've a phone call into the smith.
 
You are not answering the vital question!
Do you feel any crush on the factory shells as you close the bolt?
 
Apologies. No, I did not feel a "crush" with my loads or with the factory loaded rounds. I did speak with my gunsmith, and he agreed that we should take a couple thousandths off of the threads. He is very eager (as am I) to get this project done right.
 
OK , Thankyou. That certainly is the main problem. I would make sure you get a .005 to .007 thou crush.
 
Last edited by a moderator:
Chamber length

I just built my 3rd 223 AI a 700 rem Shillen varmit wt. bbl. I experienced the same thing w/mine Although after looking everything over I realized that not only was I too long in head space That I also have a long throat making touching the lands w/short bullets almost impossible since this was done on a 1/14 twist bbl. IM VERY DISAPPOINTED, using a reamer from midway Ive learned the hard way that you get what you pay for a DO ALL REAMER, they say that reamers are throated for the longer bullets w/tighter twist , now I have to decide if I want to pull it again after reducing the headspace to get a shorter throat. Being new at this you learn quick w/ mistakes on quality bbls.The gun shoots only slightly below MOA at this time.
 
I'm quite sure that a huge number of you guys know this, but since it hasn't been mentioned in this thread... and for the benefit of jpipes: The "Ackley" series of cartridges (I think he didn't exactly design and chamber all of them, but they follow his design principles) are designed so that the standard round's "go" gauge is used as the Ackley's "no go" gauge, and a "go minus .004" (shorter) gauge is used as the Ackley "go" gauge. And the chamber can be made perhaps .002" shorter than that, as long as you don't mind the extra effort when closing the bolt on a factory round.

This "crush" is integral to the design and allows the factory case to be properly supported during initial fireforming. Any "Ackley" rechamber of a factory barrel in which the barrel has not been set back, or any "fresh" chamber of a new barrel set using the standard "go" gauge will be too long and will not support the case correctly during fireforming.
 
Back
Top