It’s a simple system with wildly complicated friction factors. So the calculations are clear (might need an explicit FEA to solve the simultaneous neck expansion and bullet pressure) but the amount of friction could be different between, say, seating and firing.Interesting concept!
I would ask 2 additional questions. How much pressure would it take to get bullet into the bore and completely out of case. Is that enough pressure to open neck?
I have read numerous articles from industry sources over the last many years about this. They have always stated the neck expands first. So until I see contrary validated information I will go with that. I do know this. It is what it is and any conjecture shooters formulate in their heads will neither matter or probably be correct.
Industry experts say tuners don't workI have read numerous articles from industry sources over the last many years about this. They have always stated the neck expands first. So until I see contrary validated information I will go with that. I do know this. It is what it is and any conjecture shooters formulate in their heads will neither matter or probably be correct.
I have read numerous articles from industry sources over the last many years about this. They have always stated the neck expands first. So until I see contrary validated information I will go with that. I do know this. It is what it is and any conjecture shooters formulate in their heads will neither matter or probably be correct.
Please provide citations as they hopefully contain data…I have read numerous articles from industry sources over the last many years about this. They have always stated the neck expands first. So until I see contrary validated information I will go with that. I do know this. It is what it is and any conjecture shooters formulate in their heads will neither matter or probably be correct.
I think exactly the way you do about it. Because the pressure ramps up so fast, I believe it expands from the back of the cartridge forward and because the brass gets thinner as it progresses towards the neck it has the ability to stretch the brass along the web forcing the case head back to the bolt face. This being the reason we only bump the shoulder back just enough to chamber properly and minimize the brass stretch.Thinking it starts with a pressure wave from the primer, then the expanding gases, which will push on the shoulder and open the base of the neck, which then travels as a wave alongside the bullet, opening the neck, and it's the the small escape of gas in the process of opening of the neck, that dirties the exterior of the neck. If the bullet was blocking gases at that point, you get collapsed shoulders. Primers can move bullets, but, I'm not convinced it's fast enough on heavier bullets, to move the bullet much. I don't know how much pressure it takes to move the shoulder and open the case neck, but, the neck carbon would indicate to me it's pretty close to what it takes to start to move the bullet, apparently a hair less, but enough to seal the neck/shoulder juncture first. Thinking brass thickness on neck and shoulder will have some bearing on that timing also. If the rebounding wave theory is right, the first wave from primer ignition has to seal the shoulder, the second one that pushes the base back to the bolt face and stretches the case, has to be the one that does the bulk of the work on the bullet on the return trip to the neck. Sure there is likely a whole bunch more than that involved that I don't know squat about, and some points I probably missed or got wrong. But, that's how my old addlepated beanbox interprets it.
It takes the same amount of pressure it took when the bullet was installed into the case. Probably not much while the increasing pressure as bullet goes down the bore, would expand all exposed internal brass, including the neck.Interesting concept!
I would ask 2 additional questions. How much pressure would it take to get bullet into the bore and completely out of case. Is that enough pressure to open neck?
Hornady is the only one I know, but I can prove for my own satisfaction they are wrong. Thus I don't view them as experts but corporate salesmen. Of course you can if you choose. Do you have an opinion or just looking to argue? If the latter I don't have time for you.Industry experts say tuners don't work
I don't know the science to really have an opinion which is true.
However, I can say that if the neck expands first then that means donuts don't matter. Who said they do, wasn't me. I have never had a donut problem. In a lot of this there may be no accepted science just many folks ideas about things I don't waste time on. My concern is what my target says and am I tuned into my flags.
I don't think the vast majority of 'industry' people who are talking to the public have much useful to say. They're selling things and/or oversimplifying the actual reality and mostly their information aligns with the story that helps them make business.Hornady is the only one I know, but I can prove for my own satisfaction they are wrong. Thus I don't view them as experts but corporate salesmen. Of course you can if you choose. Do you have an opinion or just looking to argue? If the latter I don't have time for you.
I used to shoot primer powered only Speer Plastic bullets in my old shop for fun out of my 1911's. One time I grabbed the Magnum Rifle primers on accident, It went completely though my little target trap and then made a perfectly round hole through my old wooden shop door, Probably around 3/8 thick, Of course the report was much louder too. I couldn't believe it.Cartridge brass- C26000 material starts to yield at 15,000 PSI when soft, annealed.
Primers produce around 23,000 PSI on firing, in the pocket. . No powder.
In 243 Win., a starting load of IMR 4350 with a 68/70 gr bullet will not expand fired necks. NO annealing .
A near maximum loading will expand necks.
Comes down to PSI and powder burn rate.
https://discover.dtic.mil/
Primer Output and Initial Projectile Motion for
5.56- and 7.62-mm Ammunition
These studies have shown that the primer output alone can greatly influence the initial motion of a small-caliber projectile. The primer is capable of producing enough force to debullet the projectile and begin the engraving process prior to any significant propellant burning.