Thank you ! You should read the entire book .
Primer Output pushes bullets into rifling.
- Thread starter 243winxb
- Start date
Remember , this case had to compress from the bolt face to the shoulder , reducing the size from case head that's exposed to the shoulder . So the base dia all the way to the shoulder would now be reduced .
I use to fireform brass in a solid piece of steel with just a chamber with just a small dia ( aprx .025 ) vent . Used primers only . went from a std 30-30 to Ackley .
DO NOT TRY , it took a good mentor and some experiments to do safely
I use to fireform brass in a solid piece of steel with just a chamber with just a small dia ( aprx .025 ) vent . Used primers only . went from a std 30-30 to Ackley .
DO NOT TRY , it took a good mentor and some experiments to do safely
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I believe a 30-06 case would be shoved in a long way
It take considerable force (and a VERY short, like .015 under SAAMI!) for an -06 case to even jam enough to fireform properly......I remember two people on BRC to whom this happened.
http://benchrest.com/showthread.php?72097-Possible-Dangerous-Cartridges-Caution!
Good proof that the primers make some serious pressure.
The Federal primer lists Nitroglycerin as a component. Other brands dont.
Nitroglycern would seem to add sensitivity, with a faster reactive response when struck by the firing pin?
https://www.federalpremium.com/safety-information/sds
Alinwa, good link. Ty.
The book I was referencing has the ingredients of primers , unfortunately it's from the 1950s. I do have a more recent formula list but ? . It could be in the BENCHREST shooting primer .
Except when bullets stay in the case neck.
What's the volume ratio from the space inside a seated primer dented by a firing pin to that of a cartridge case?
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No idea.
With no powder in the case, the output from the primer firing would be absorbed by a large case.
The powder fills the case volume. The powder column moves forward , pushing the bullet out of the case mouth.. The 5.56 had almost 100% case fill. The 7.62, less.
Other cartridges and powder types would have to make a difference.
This is how i understand it. Could be wrong.
With all the disparate results of primer ignition effects one would have to suggest that either primers are not as uniform as we'd like to believe or there is some moderating effect in each individual case. My experience has been that revolvers are more likely to put the bullet firmly into the bore than most rifles. Most of the rifle misfires Ive seen just mess up the powder and at most have just put the bullet in the throat. Usually the bullet hasnt moved. Even at one point tried firing cases with primer and no powder. Limited trial but no bullets left the case. Id have to guess that the wild differences reported that there must be some degree of waveform or pulse effect that is able to move some bullets as far as reported.
ronemus
Gold $$ Contributor
Bullet pull force is on the order of 30-40 lb (can be higher), so the internal pressure would have to be ~500 psi in a .223 (~1/16 sq in) or ~300 psi in a .308 (~1/10 sq in) to start moving the bullet. The primer doesn't produce a lot of gas, so it is reasonable that the pressure in an empty rifle case might not be high enough to release the bullet (in the one .223 load I've left the powder out of, the bullet didn't move). In a pistol load with a small case volume and a larger diameter bullet, or a rifle load with powder, the is much less free volume, so the pressure likely does get high enough for release.
I have stuck a bullet into the rifling using a CCI-450 primer and no powder in a 6BRX. I heard a pop but no report. Waited for a hang fire that didn't happen. Left the firing line and opened the bolt about a minute later. It flew back with the pressure trapped between the case and the stuck bullet. My gunsmith chucked the barrel up, made a long drill bit and drilled the center of the bullet and used a screw mounted to his lathe to extract the bullet. He said it was solidly into the rifling.
30 caliber bullet, .0745 square inch. ~1/13.4th
22 caliber bullet, .0394 square inch. ~1/25th
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