Ruminations

Not sure how to pose this or if I can accurately state what is in my head but I will try. I'm looking for thoughtful comments, not argument.

Over my years of gun owning, tinkering, reloading, casting, shooting and reading much about all the preceding I have probably encountered most all the "common knowledge", oold wives tales and outright myths related to loading and shooting cast lead bullets. I DO Not have nearly the experience some of y'all have in terms of shooting/experimenting with cast rifle bullets. All that said....

I have read/heard about gas cutting, flame temperature, bullet base melting etc. And I have read upon powder ignition dacron filler melts in the case and/or bore. Two occurances got me wondering. They were(1)combustible toilet paper used as powder positioned produced a fine white cloud ahead of the muzzle upon firing and (2) combustible cotton(ball) used fas filler produced a loud of white fiber in the air ahead of the muzzle. This got me thinking if powder combustion melts(supposedly) dacron filer or bullet bases then why are toilet paper particles not consumed by flame in the barrel or at least propelled from the muzzle as burning debris? Or the same for cotton?

There Is unquestionably high temperature present upon ignition of powder. But is the temperature present in a blowtorch like flame or is it in the mass of ignited powder being reduced to rapidly expanding gas that propels the bullet?
My sense is both but if the amount of time the heat is applied is not sufficient to ignite paper is it sufficient to produce the other effects attributed to heat/flame?
,Are the effects of ignition due to application of high temperature or to the lead alloy bullet becoming "plastic" under intense pressure?

Rather than paper, kapok is a cheap substitute. Find some old cattails, shred the heads, shazam, instant kapok!

I have recovered bullets with the grease I put on the base apparently unaffected. If the powder burn is not of a sufficient duration to melt grease I cannot see it doing all it is blamed for. OTOH, I am aware that ball powders and short bullets cause erosion in K Frame S&W pistols. I have a very accurate 280 Remington with enough throat erosion that a 175 gr bullet has almost 1/2" before it reaches the lands. It is still under MOA. Some times everything that is written is true and in some occasions it may not be applicable to your situation.

Very good questions.
Sometimes there is unburned powder remaining in the barrel after firing, one has to ask the question, WHY?

If you fire a gas checked bullet of soft alloy, at high pressure, recovered bullets often have lead on the gas check. If there were any kind of blow torch or hot gases melting bullets, recovered gas checks would be squeaky clean. Dacron is different in that it is such a fine material, it hardly takes anything to melt. Toilet paper is not a fine material. It is too solid.

Regarding why cotton to paper don't melt. Melting is not something that those products do. They burn, ablate or vaporize but they don't melt like metals or plastics. Actually some "plastics" don't melt but instead ablate. Poly definitely melts and does so at a pretty low temperature. Lead melts at a pretty low temperature as well but inside a barrel the thermal conditions are very complicated, a lot of variables and in most cases neither the poly or lead will melt. The biggest cause of melting is if a goodly amount of hot gas blows by the base of the bullet bring more hot gas to the base of the bullet and past the filler.

Tim

FWIW a bit of Googling revealed that the ignition temp of paper is 450°F and that of cotton is given as 410°F. Cotton is said to self-combust at 764°F.
We are familiar with Temps at which lead and lead alloys become liquid.

Note: this thread was not stated to find a better filler. Just discussion of what's happening in there when things go bang.

The burn "inside" is happening almost instantaneously. The combustible/meltable items, (like dacron, PC, alloy boolit base) most likely will not get up to temperature in time to combust/melt. But in some circumstances, they will.

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blowtorch like flame

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OK, this doesn't happen, melting lead. However, cutting torch cuts by hot gas MASS and temp. Metal doesn't melt but only hot enough to reduce strength to the point of being blown away. Same with gas cutting of cast. High pressure and small exit (leak) increases velocity of the gas, mass is same so ENERGY in the gas flow increases.
Why don't our fillers burn? Solids don't burn. They have to vaporize first and they don't do that rapidly. The materials powder is made of vaporize very fast. Their vaporization rate increases with pressure and proximity of adjacent grains. The chemical energy potential of smokeless powder is MUCH greater than that of our filler material.

I think with Gas Cutting it is the high speed of the gasses dumping BTUs in a small area.

Gun Powder supplies it's own oxygen but there might not be any left over to burn paper.

Guarantee that if you could increase the % oxygen you would get different results.

Thinking of gas cutting as "dumping BTUs in a small area" is akin to a leak in a dam becoming bigger as all the water tries to escape thru one hole. That raises another question in my mind. The lead/lead alloy bullet becomes "plastic" or putty-like under sufficient pressure and that pressure is multiplied if concentrated in a tiny area such as where expanding gas escapes past base band or gas check. So is gas cutting caused more by concentration of BTUs or high pressure escaping gas forcing aside the bullet material?

As to whether or not filler material burns being due to lack of oxygen, maybe/probably? I put it that way as there Is oxidizer present in the propellant but will it support combustion in adjacent materials? I dunno.
Actually the part the fillers play in my original post is that they got me wondering what Really is going on in there. Unquestionably high temperature is present ad evidenced by touching a barrel after firing several rounds or by picking up an ejected case. What I am thinking on is the time factor. Ignition and consumption of a powder charge takes milliseconds generating heat and a sudden release and expansion of gas thus launching the bullet. Given the speed of expansion of gas that is accelerating everything in it's path would the application of heat have time to do all we have supposed it to do before all is propelled from the muzzle?
Regarding whether dacron melts in that same millisecond, some say yes and some say no. I dunno.

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Originally Posted by littlejack

Very good questions.
Sometimes there is unburned powder remaining in the barrel after firing, one has to ask the question, WHY?

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Easy answer it did not all burn.