an increased mv with same load in fireformed case?

[bigedp51]

I googled "Guns and Ammo campfire and bean-eating contest" and the link below was all I could find that related to what brians356 may have been referring to.

Meaning the spreading of micronic particulate matter and inhalation toxicity.

The Campfire
https://www.youtube.com/watch?v=VPIP9KXdmO0

 

[mac86951]

I would have to agree with energy used to form the case.

 

[Ned Ludd]

If I understand your original post correctly, you opened up the necks on the original brass to 6mm and a slight neck turn prior to fire forming. After fire forming, you used a FL sizing die. Any chance some of the difference in MV is due to a difference in neck tension?

 

[Ackman]

Brass is soft. A case is easily crushed with hand strength and pliers. "Energy diverted" What the.......? With 50,000+ psi happening inside a fired case, the tiny amount of energy expended to move the casewall out a bit is irrelevant. Not even a factor.


Poking around for other things I came across this. Scroll down to #1 and see what David Tubb says about shoulder angle and velocity/powder charge. I've thought something like this was going on.
http://precisionrifleblog.com/2013/12/17/best-rifle-caliber-what-the-pros-use

 

[dmoran]

Brass is soft. A case is easily crushed with hand strength and pliers. "Energy diverted" What the.......? With 50,000+ psi happening inside a fired case, the tiny amount of energy expended to move the casewall out a bit is irrelevant. Not even a factor.

Questions for you:
- if it takes so little effort to expand new brass like you say, how come it takes fairly significant pressure (of say +25,000-psi) to even begin to form an Ackley fully, and why are they not fully formed after one firing from an upper load?
- why does it take multiple blows with a hammer when hydro-forming?

 

[mac86951]

Brass is soft. A case is easily crushed with hand strength and pliers. "Energy diverted" What the.......? With 50,000+ psi happening inside a fired case, the tiny amount of energy expended to move the casewall out a bit is irrelevant. Not even a factor.

Questions for you:
- if it takes so little effort to expand new brass like you say, how come it takes fairly significant pressure (of say +25,000-psi) to even begin to form an Ackley fully, and why are they not fully formed after one firing from an upper load?
- why does it take multiple blows with a hammer when hydro-forming?

+1 thank you

 

[Ackman]

Brass is soft. A case is easily crushed with hand strength and pliers. "Energy diverted" What the.......? With 50,000+ psi happening inside a fired case, the tiny amount of energy expended to move the casewall out a bit is irrelevant. Not even a factor.

Questions for you:
- if it takes so little effort to expand new brass like you say, how come it takes fairly significant pressure (of say +25,000-psi) to even begin to form an Ackley fully, and why are they not fully formed after one firing from an upper load?
- why does it take multiple blows with a hammer when hydro-forming?

Answer for you:
- I don't know. I don't use hydro-forming, and fireform with bullets and full strength loads. In upwards of 10,000 cases I've never ever had even one come out less than fully formed.

Different chamberings don't act the same way. Most often charge and velocity - FF vs. formed - were pretty much in line with what I'd expect the progression to be. Some FF loads - velocity and charge - were actually the same as with formed brass........243AI and 257AI for instance. I've even experienced FF loads that were a tad faster. Combustion takes place in a tiny fraction of a second. That burn energy is contained and can only go one place, out the casemouth. I don't believe that "energy diverted" has anything to do with anything.

I think the best answer to what the OP is experiencing lies in David Tubb's statement on that blog. A more efficient shoulder angle. The man certainly knows his stuff.

 

[dmoran]

Answer for you:
- I don't know. I don't use hydro-forming, and fireform with bullets and full strength loads. In upwards of 10,000 cases I've never ever had even one come out less than fully formed.

Different chamberings don't act the same way. Most often charge and velocity - FF vs. formed - were pretty much in line with what I'd expect the progression to be. Some FF loads - velocity and charge - were actually the same as with formed brass........243AI and 257AI for instance. I've even experienced FF loads that were a tad faster. Combustion takes place in a tiny fraction of a second. That burn energy is contained and can only go one place, out the casemouth. I don't believe that "energy diverted" has anything to do with anything.

I think the best answer to what the OP is experiencing lies in David Tubb's statement on that blog. A more efficient shoulder angle. The man certainly knows his stuff.

Interesting.....
But have to say, your the first person I've ever heard to make those claims....
I myself used 243-AI's for 6 years, and 6Dasher's for 11 years since, and never once seen what you have. And have never seen an Ackley or Improved case 100% formed from 1 firing, no matter what the load.
Just me I guess....
Donovan

 

[gotcha]

No Donavan, It's not just you ...... If ALL the energy was diverted out the case mouth there'd never be a need for re-sizing.

 

[Ackman]

Answer for you:
- I don't know. I don't use hydro-forming, and fireform with bullets and full strength loads. In upwards of 10,000 cases I've never ever had even one come out less than fully formed.

Different chamberings don't act the same way. Most often charge and velocity - FF vs. formed - were pretty much in line with what I'd expect the progression to be. Some FF loads - velocity and charge - were actually the same as with formed brass........243AI and 257AI for instance. I've even experienced FF loads that were a tad faster. Combustion takes place in a tiny fraction of a second. That burn energy is contained and can only go one place, out the casemouth. I don't believe that "energy diverted" has anything to do with anything.

I think the best answer to what the OP is experiencing lies in David Tubb's statement on that blog. A more efficient shoulder angle. The man certainly knows his stuff.

Interesting.....
But have to say, your the first person I've ever heard to make those claims....
I myself used 243-AI's for 6 years, and 6Dasher's for 11 years since, and never once seen what you have. And have never seen an Ackley or Improved case 100% formed from 1 firing, no matter what the load.
Just me I guess....
Donovan

You've NEVER SEEN a case formed perfectly after 1 firing? You're the first person I've ever heard make that claim. Don't know what to tell you.....I guess if you haven't, you haven't. Maybe you're doing it not quite right? I've never FF'd with reduced loads or fillers, and in more than 25yrs of shooting AI's have never had a case that wasn't perfectly formed after one firing. Not even one. People I know who shoot AI's have no problems forming brass either. Even an extreme wildcat like the 240Gibbs, one firing is all it took.

 

[dmoran]

You've NEVER SEEN a case formed perfectly after 1 firing? You're the first person I've ever heard make that claim. Don't know what to tell you.....I guess if you haven't, you haven't. Maybe you're doing it not quite right? I've never FF'd with reduced loads or fillers, and in more than 25yrs of shooting AI's have never had a case that wasn't perfectly formed after one firing. Not even one. People I know who shoot AI's have no problems forming brass either. Even an extreme wildcat like the 240Gibbs, one firing is all it took.

Nope.... never seen the shoulders 100% formed after 1 firing. Seen them up to say 98% formed, but never totally 100% after only 1 firing (even from stiff enough loads that wrecked primer pockets).
And have seen them considerable less then formed, when lighter methods such as pistol powders, COW, hydro-formed, mild loads, etc, have been used. Which is surprising I guess, since you say cartridge brass adheres to shape with absolute miniscule amount of pressure. But I guess I'm not alone after all, since Mac and gotcha replied with agreements !.!.!
Donovan

 

[jo191145]

I lifted this from another post. Seemed interesting and pertinent. But I guess if brass expands as easily as a party balloon this never happens. The thread was discussing blowby in a 223 wssm.
I was just having this discussion on another forum where the shooter was using max load data from Berger and getting soot all the way to the rim. Guess that never happened either. Always learning something new.

The problem is the thick necks. This problem is so pervasive in this cartridge that Sierra will not publish data on this cartridge. I got this directly from Sierra when I was having this sproblem. The Tech told me that with some powders there was less than one grain difference between the neck not sealing against the chamber and max load. With all of the variables in handloading Sierra did not feel that it was prudent to publish loads for this cartridge. I gave up on the cartridge.

 

[dkhunt14]

I have seen brass formed to close to headspace length when fireformed or Hydro formed. I have never seen it formed with a complete sharp shoulder. They usually stay somewhat rounded. If you hit the brass really hard on the first firing primer pockets seem to go away quicker. It just seems to be hard on brass. I believe it takes at least 2 firings to get them sharp at the shoulders. Matt

 

[fguffey]

You will probably find that your F/F'd case is also slightly shorter, just like the AI cases.......

Does anyone measure before and again after? I form cases, I have chambers that require firing to form. My cases shorten in length from the end of the case neck to the case head .035", I have one chamber that requires fire forming after forming, those cases shorten .045" in length from the end of the neck to the case head. The necks are very short, the necks length measure .217".

F. Guffey

 

[Brians356]

Answer for you:
- I don't know. I don't use hydro-forming, and fireform with bullets and full strength loads. In upwards of 10,000 cases I've never ever had even one come out less than fully formed.

Different chamberings don't act the same way. Most often charge and velocity - FF vs. formed - were pretty much in line with what I'd expect the progression to be. Some FF loads - velocity and charge - were actually the same as with formed brass........243AI and 257AI for instance. I've even experienced FF loads that were a tad faster. Combustion takes place in a tiny fraction of a second. That burn energy is contained and can only go one place, out the casemouth. I don't believe that "energy diverted" has anything to do with anything.

I think the best answer to what the OP is experiencing lies in David Tubb's statement on that blog. A more efficient shoulder angle. The man certainly knows his stuff.

Interesting.....
But have to say, your the first person I've ever heard to make those claims....
I myself used 243-AI's for 6 years, and 6Dasher's for 11 years since, and never once seen what you have. And have never seen an Ackley or Improved case 100% formed from 1 firing, no matter what the load.
Just me I guess....
Donovan

You've NEVER SEEN a case formed perfectly after 1 firing? You're the first person I've ever heard make that claim. Don't know what to tell you.....I guess if you haven't, you haven't. Maybe you're doing it not quite right? I've never FF'd with reduced loads or fillers, and in more than 25yrs of shooting AI's have never had a case that wasn't perfectly formed after one firing. Not even one. People I know who shoot AI's have no problems forming brass either. Even an extreme wildcat like the 240Gibbs, one firing is all it took.

I for one am with "dmoran" here.

I've had cases not perfectly formed with one firing of factory ammo (250-3000) in an AI chamber. In fact, that's the reason I switched to "bulletless" forming using Bullseye and inert filler - I insisted on a sharp corner on the 40-deg shoulder with one firing, and to get that I found the optimum load of fast powder.

A case not sharply formed at the body/shoulder junction is not "perfectly formed". You and your acquaintances who have had success with one firing of a standard load just might not be as particular about the results as some of us. Eye of the beholder.

 

[Brians356]

Brass is soft. A case is easily crushed with hand strength and pliers. "Energy diverted" What the.......? With 50,000+ psi happening inside a fired case, the tiny amount of energy expended to move the casewall out a bit is irrelevant. Not even a factor.

The OP did not stipulate how much velocity was apparently "lost" during fireforming, compared to second firing. He only said it was enough to open up the groups. That could have been as little as 50 fps, but let's be generous and say 100 fps. With a 6x47 let's assume (conservative) velocity around 3000 fps. That 100 fps is only a ~3% loss. You don't think 3% of energy might be required to expand a case in an improved chamber? (And it reasonably could be as little as 1% using real numbers.)

 

[fguffey]

With a 6x47 let's assume (conservative) velocity around 3000 fps. That 100 fps is only a ~3% loss. You don't think 3% of energy might be required to expand a case in an improved chamber?

Energy: A smith in Arizona suggested I was into some risky stuff. He took the time to email drawings and loads, I did not agree with him. Energy was never part of the conversation. I called Hodgdon, Hodgdon said I was correct, because of factors. The smith understood factors and I understood factors, we never designated energy into percentages.

F. Guffey

 

[Brians356]

With a 6x47 let's assume (conservative) velocity around 3000 fps. That 100 fps is only a ~3% loss. You don't think 3% of energy might be required to expand a case in an improved chamber?

Energy: A smith in Arizona suggested I was into some risky stuff. He took the time to email drawings and loads, I did not agree with him. Energy was never part of the conversation. I called Hodgdon, Hodgdon said I was correct, because of factors. The smith understood factors and I understood factors, we never designated energy into percentages.

" ... because of factors" huh?

Fair enough. I was in fact reluctant to break this down in terms of percent of energy vs velocity, "as if" there is a linear relationship, or anything close to linear. I was only trying to make the point that there was not necessarily a large velocity difference, and therefore not necessarily a lot of work (Hah!) being diverted to expanding the case which would otherwise have increased muzzle ener ... oops, sorry (!) er, ... velocity - how's that?

(Please, do call your experts before replying. Might want add those numbers to speed dial.)

 

[fguffey]

I was only trying to make the point that there was not necessarily a large velocity difference, and therefore not necessarily a lot of work

brians356, thanks for not loosing it, there are topics on this forum that can not be discussed like annealing, I make my own annealing equipment. Then there is the do-nut. Then there is this topic, fired and fire formed without factors.

F. Guffey

 

[Ackman]

I for one am with "dmoran" here.

I've had cases not perfectly formed with one firing of factory ammo (250-3000) in an AI chamber. In fact, that's the reason I switched to "bulletless" forming using Bullseye and inert filler - I insisted on a sharp corner on the 40-deg shoulder with one firing, and to get that I found the optimum load of fast powder.

A case not sharply formed at the body/shoulder junction is not "perfectly formed". You and your acquaintances who have had success with one firing of a standard load just might not be as particular about the results as some of us. Eye of the beholder.

Well, we're pretty particular.................

Funny....I've seen posts on different forums by people who thought using filler was the way to go, and complained about getting incompletely formed cases with that method. Then others would come on and say how they fireform with bullets and get perfect results. I know you guys are ex-purts...but if both you and mr. moran have had problems fireforming with bullets, sounds like - just maybe - neither of you are doing it right.