Saw this video and found it pretty interesting. I know its facebook so if anyone can post a direct link that would help.
www.facebook.com
Good illustration. There is no way that a primer could generate enough force to push THAT bullet into THAT barrel. BUT, I have seen bullets pushed into the rifling by the energy exerted by a primer alone. So, bearing in mind the above two examples, I conclude that the question that Alex posed, is not an either/or situation where it is neck first, or bullet first, 100 percent of the time. It would seem the evidence points towards some barrel, bullet, primer and powder combinations being able to push the bullet into the rifling before the powder burn happens, and some combos incapable of doing that. One combo moves the bullet first, the other can't move the bullet, so the pressure builds, and opens the neck first.I did a test once where I installed a short piece of chambered barrel in my old RCBS Rockchucker press. Made a punch to fit in the shell holder. It took an unbelievable amount of force to push a 6.5 bullet into the barrel. So much force was required I had to lube the barrel for each bullet to continue the test. Just a SWAG but I'd say it takes maybe 50-75 times more force to push a bullet into the barrel than running an expander mandrel into the neck.
My vote is the neck expands first.
The gas leaks between the bullet and case neck and flows around the case neck into the chamber. As the pressure and gas volume increase the case neck is fully expanded and the bullet is pushed into the barrel.I can ask one question and the case is solved!! IF THE NECK OPENS UP FIRST, HOW DO YOU GET BLOW BY RESIDUE ON THE OUTSIDE OF THE NECK AND SHOULDER?????
The gas leaks between the bullet and case neck and flows around the case neck into the chamber. As the pressure and gas volume increase the case neck is fully expanded and the bullet is pushed into the barrel.
You bet. With our .085 neck length .30 WolfPup cases....the loads needed to be up there. Attempts with slower burn rate powders always resulted in gas leakage around the necks and past the shoulder/body junction.Shooting low pressure loads may also change the answer
If I’m following you, rise time, also effects rate of acceleration. In a car that would be the 0-60 time.You bet. With our .085 neck length .30 WolfPup cases....the loads needed to be up there. Attempts with slower burn rate powders always resulted in gas leakage around the necks and past the shoulder/body junction.
It wasn't so much the actual pressure but more the powder burning rate and what I term the 'rise time'....for lack of a better description.
Good shootin'-Al
EVERYBODY SEEMS TO FORGET ABOUT THE UNBURNT POWDER THAT IS CRAMMED FORWARD IN THE CASE ON THIS OPS DEBATE!!!!
Look at some physical properties that apply in this debate!!! Gases are highly compressible, liquids are slightly compressible, and solids are not compressible!!
The compression properties are about cramming in more phase elements into a fixed container! If you take a closed container of gas, you can cram more in, but the pressure will increase proportionally!! With a liquid, like water, you can get a little more in, but the pressure will spike exponentially!!! If that container is fill with say solid lead, trying to add more, the pressure would have to be extremely, almost infinite to add a little!!! This is based on Thermodynamic!! Yes, adding more air increases the temperature proportionally!!! Adding more liquid spikes the temperature exponentially!! But adding more solid, to that already full volume, the temperature would be enormous!!!!Liquids are not compressible, Solids can be compressed. But by your
definition, it does bring up another point. Although the rifle powder
is a solid, it's broken down into a particulate, then can be compressed
more easily, such as a compressed load.......Too many worms in this can,
but a good conversation anyways......
Thats always been my opinion. On target the actual neck tension (interference fit) always showed as more important than seating force (friction) in my tests and others. I do remember a friend that had a rifle with a very long throat and the bullet was seated way out. It was also a slower powder as well. That bullet did slide out. We know that because the necks didnt expand. Pressure equalized on the outside of the necks.Stan Ware and I learned a lot with our .085 neck length .30 WolfPups. Necks absolutely expand first. -Al
Was the residue outside of the neck as dirt as the inside?Thats always been my opinion. On target the actual neck tension (interference fit) always showed as more important than seating force (friction) in my tests and others. I do remember a friend that had a rifle with a very long throat and the bullet was seated way out. It was also a slower powder as well. That bullet did slide out. We know that because the necks didnt expand. Pressure equalized on the outside of the necks.
Yes.So you're saying the bullet magically hangs in space and gravity does not effect it???
If people test things, stuff gets a lot clearer. You can take half a dozen cases and starting with as close to zero clearance as you can over the heel of a seated bullet....turn each subsequent case neck for .0005 more clearance.Thats always been my opinion. On target the actual neck tension (interference fit) always showed as more important than seating force (friction) in my tests and others. I do remember a friend that had a rifle with a very long throat and the bullet was seated way out. It was also a slower powder as well. That bullet did slide out. We know that because the necks didnt expand. Pressure equalized on the outside of the necks.