10mm gel tests

[The_Shadow]

I did actually think about the subsequence grass fire scenario, that Raggedyman graciously mention earlier, yes that scenario is very real, but what would I know about that one, after putting out fires for over 30 years!

I have seen glass bottles deformed as a result of a ordinary grass fires which would require about 1200 degrees F, easily doable in low level burning field grasses and brush.  That would be plenty enough to melt most alloys of lead out.

[Geeman]

Interesting take on a few things here. 

I'd like to share a piece by Berger Bullets about the melting lead subject.  Its the second page and second paragraph.

http://www.longrangehunting.com/articles/match-grade-berger-hunting-vld-history-1.php

I give great respect to the knowledge of this group of folks at Berger.  I'm not equating 5" barrels at 30k PSI vs 1000yd center fire rounds at 60k PSI smoking out of a 30"tube as to how hot the projectile gets.  Its barrel friction, not air friction causing the issue.

Greg

[Raggedyman]

I think you meant 27,000 MPH 

Nope. I think I got the math right. According to Wiki, re-entry occurs at about Mach 25, or 8,200 meters per second. Using Google to convert meters to feet yields 27,000 fps.

[Raggedyman]

Interesting take on a few things here. 

I'd like to share a piece by Berger Bullets about the melting lead subject.  Its the second page and second paragraph.

http://www.longrangehunting.com/articles/match-grade-berger-hunting-vld-history-1.php

I give great respect to the knowledge of this group of folks at Berger.  I'm not equating 5" barrels at 30k PSI vs 1000yd center fire rounds at 60k PSI smoking out of a 30"tube as to how hot the projectile gets.  Its barrel friction, not air friction causing the issue.

Greg

That was a really cool article and fairly surprising. Two things seem noteworthy, though. The first is that it sounds as though that particular projectile is a rarity and it is unlikely that the same thing would occur with other bullets. More noteworthy, I think, is the fact that the bullets never make it to the target and would never be found with a pool of molten lead leaking from the jacket.

[The_Shadow]

BTW, escape velocity for the shuttle to low earth orbit at about 80 miles above the surface and is also at or above 17,500 MPH.  And that is why your bullets fall to earth...

[4949shooter]

One thing I find odd, is that snipers all over the world are sustaining killing hits on enemy combatants at well over 1000 yards. If all the bullets were melting the lead out of them, these bullets would never even make it to the intended targets much less penetrate causing traumatic injury or death.

I agree, maybe these particular bullets that melted were out of spec, melted in a  fire, or whatever.

[Geeman]

Apples to oranges. 

3000 fps and those long,sleek bullets require high twist rates to stabilize them.  At 8" twist that bullet spins at 270,000 rpm as it leaves the barrel  The whole core doesn't need to be liquid to cause a problem.  It just comes apart with the first shift in center of gravity.  The bullet in barrel time is around 1.5 milliseconds.

Compare to 1300 fps, 16 twist barrel, .5 ms time in barrel, around 60,000 rpm for a typical 10mm pistol. 

The melting force is friction with the barrel, not re-entry type air friction.  I doubt the core melting in a pistol barrel.

Greg

[mrpipesmkr]

Here is an article that mentions heat build up from friction in the bore and atmosphere as a cause of  bullet failures.

http://www.longrangehunting.com/forums/f19/bullet-failure-article-20778/

[The_Shadow]

What comes to mind for me is these are rifle bullets being taken to the extreme of higher RPM's from higher rates of twist.  Toward the end of the article it seems they almost touched on the possible cause but then dismissed what they started to consider as the upsetting cause.

Poor bullet fabrication such as too low or too high seating pressure. Low seating pressure can create a poor mechanical bond and/or air pockets that further destabilize the bullet. Seating pressure that is too high effects the copper jacket by producing a weakness where the nose can separate from the body. These conditions can be most easily detected by weighing your bullets, as too low or too high seating pressure is mostly the result of an extreme change in the mass of the lead.

Other examples of poor fabrication are any excessive lube on the cores (many bullet makers do not clean their cores before bullets are swaged) or debris between the jacket and the core can produce a weak bond, air pockets and/or significant stability issues through poor balance around the axis. Another poor fabrication condition that is easiest to avoid is lead that contains debris or significant air pockets due to double extrusion. This condition does not exist when a quality source of lead is used. Quality bullet manufacturers of which there are many can avoid all of these fabrication conditions.

In my opinion it is possible they are revving up these bullets with the high rates of twist, thus increasing the heat induced by bore contact, as the bullet is forced down the bore at higher velocity rates.  To me the heat along with the higher rate of twist is loosening the the bond of the core to the inside of the jacket, therefore even more heat is produced as the jackets begin to revolve around the core.  At some point the jacket is spinning wildly but the core has become plastic or possibly to a molten state, with deteriorating gyroscopic/centrifugal stability to the point of being steered off course or even self destructing.

We are talking about seriously high velocity and high RPM's, smaller diameter bullets with thinner jackets.  What may be needed is a jacket that is better attached to its core, so that the core is being spun equally as the outside jacket.

However this is where the solid copper or solid brass projectiles would shine, as they have no core to separate or become molten.

They could technically design an extruded jacket with an hexagonal or octogonal interior that might eliminate the jacket from revolving around the core...

So it comes down to economics ($$$) as those guys push the limits of bullet design technology!

BTW, I actually sent this crazy notion of mine to Eric Strecker of Berger Bullets what they do with the info is up to them...

[mrpipesmkr]

I'm with you on your conclusions, Shadow. 
I was using the article to show that it and many others mention that friction caused by the bullets passing rapidly through the air does create heat build up.
But bullet failures seem to be caused by dynamic stress on the jacket caused by high RPM's and heat causing the core to increase in plasticity.

[Raggedyman]

It seems clear from that article, at least, that air friction is not likely to cause any significant heat at normal velocities. The source of heat is from burning propellant and friction in the barrel.

[Intercooler]

   He seemed to get some messed up readings. Did the Glock experience some unlocking? I have no idea on the 900 FPS one...

[The_Shadow]

That was interesting that the round experienced that much difference, Was it a short on powder load?  Looking at the gel block of that shot it showed less energy to match the lower velocity...

Could it have been a poor ignition of the heavily compressed powder charge, yes Powder Pistol is a fast burning powder, but at the amount of compression, it may not have ignited all of the powder and could have blown most of the compressed pellet of powder out the barrel.  Look real close at the video at 1.24 and watch the pieces flying after the bullet strike, several big pieces of debris (possibly the pieces of the unburned compressed powder) come flying into the picture...

[Intercooler]

  Why didn't I get any with the Buffalo Bore or the COP rounds with this load?

[The_Shadow]

The bullet may have been a loose fit and moved before the powder was fully involved...hey just a W.A.G.  Wild Ass Guess

Strange things can happen, those pellets of powder they use for muzzle loaders have been known to come flying out like roman candles!  Even though the were burning they didn't burn correctly to add to the bullets momentum...