Do you believe that lead boolits actually obturate (swell up) when fired? Yes or No

[45 2.1]

Molly;851669>Well, you can believe whatever you want to I guess.

Hmmm. I believe that comment cuts in both directions.
Your correct, it does.........

>Part of a quote from the above statement: it DOES require a very soft alloy, which is not the subject under discussion. We are talking about hard alloys, from wheelweights hardness and up. I can have a hard boolit, specifically 19 to 20 BHN, that is quite ductile and expands nicely also (50WW/50PB water dropped) which meets your WW hardness requirements and still achieve GC shank obturation in specific loads.

Can't really comment here: I never played much with quenched alloys, because their hardness drifts with time with all antimonial alloys, and I figured I had enough unknowns to deal with as it was. But I am a bit confused at the apparent discrepency in your hardness ratings. You should actually learn something of this if your going to make blanket statements as you have. In your earlier note, you specified a 50/50 WW / lead alloy, and commented that it was quite soft. Now you rank that same composition as about 20 BHN. May I assume the difference is that some of them were quenched, and some were not? No, that can't be it: You specified that you needed a soft alloy to get obturation in your earlier note, and seem to be saying that you also get obturation when the same alloy is quenched for hardness. If that's so, your earlier comment that softness is necessary of obturation is rather confusing. Again, there is a lot of data out there........ read some of it and learn whats going on....................What you assume through not knowing is confusing you.

>If you want to talk about a hard alloy, from individual components, then you probably are right (for other reasons), BUT if its just hard, due to heat treatment, your idea doesn't hold a lot of water. Equating hardness with alloy components is an old idea which has little relevence with todays knowledge, however little noted it is.

I grant you that it is possible to alter the 'normal' hardness of many alloys by quenching, and that this is well known today, though not well known some years ago. For folks not taking the time to learn about it, then yes, BUT the data was there. I assume this is what you were referring to above. However, it is also well known today that the hardness increase so obtained is highly dependent on a number of factors, including the quench rate and alloy composition: Presence of a few percent of arsenic is critical, and more than a trace of tin results in a very rapid decay of quench hardness back to 'normal' hardnesses. The fact of the matter is that very few bullets are cast from precisely known alloy compositions, so the results are not well predictable, especially as you move from one batch of alloy to another. The best that can be relied on is that you can obtain fairly useful hardness increases with the typical alloy, such as the 50/50 blend you are using. You really need to learn about this instead of supposeing.....several of us have quite some years into this. What you just said is speculation when you apply it to all alloys........Lead and the alloy components you can put with it have the same virtual range of uses that steel has (nice soft steel versus very tough hard steel, remember its just steel (or lead), Ehhh)...................

This technology wasn't known when I started my quest. My early trials as a kid consisted of anything that I could get to melt. In fact, though I blush to recall the fact, my ignorance was so vast that I reasoned that the lead melted from the cores of spent jacketed bulllets had to make good cast bullets, because it was already demonstrated adequate for full power loads in jacketed bullets. My first trial produced something like 20 or 30 degrees of angle accuracy. Not minutes of angle. DEGREES. And things didn't improve a whole lot until Col Harrison published his experiments in the Rifleman. But with that to put me on a sound footing, my results in high power loads improved dramaticly, and the results of my tests began to give reproducable and readable results. I have been able to produce full power 30-06 cast loads for many years now, and have seen no need to resort to quenching. And contrary to what you seem to think, the 'normal' hardness of air cooled alloys is rather sharply defined by composition. It is also uniform and stable, properties that - in my opinion - are critical to serious testing. Refer to the first statement here. There is a lot more to alloys and there treatment out there than you know.........

>This is also possible with WW and harder alloys useing rather unusual techniques. Take a very large hollow point heavy pistol boolit and fire it backwards with a heavy charge in a magnum pistol. You might find out some things.

Oh, come on. Do you really think I have never heard of reversing a HB wadcutter? I generally got 3/4 inch mushrooms from a .38 slug. Read the original statement until you understand it, you are way off course. And do you really consider me so dense that it wouldn't occur to me that the same phenomenon wouldn't be effective in any caliber? I'm not talking about effect, i'm useing a large hollow point reversed boolit to show you that hard alloys can obturate. That depends on how strong the nose wall is versus the pressure applied to it. Think thick hard versus thinner hard and see where that leads you. Simple strength/pressure relationships occuring there. Or that I couldn't predict that the expansion could be tailored by adjusting the diameter, shape and depth of the hollowpoint? Give me a little credit. Nope....not with what you just said. Lead alloys can be as different as night and day....

Nonetheless, I am interested in what you say. Would you be willing to send me some of your bullets, as cast, as quenched, and as recovered? I would indeed like to examine them. I can send you a PM with my address if you are interested. When you've read the various sources on the web and have actually tried (instead of assuming) various alloys involving hardness, ductility, expansion, etc., then i'll discuss the situation with you. You need some better information than what you've had so far. Try here: http://www.lasc.us/CastBulletNotes.htm, various NRA publications authored by Dennis Marshall, this site and other various web sources. There is no substitute for actually trying something out yourself.

[bohica2xo]

OK kids, this thread has been entertaining, but it seems to have taken a dangerous turn.

Do NOT try shooting submerged firearms!

Yes, I am well aware of the fact that you can shoot a 9mm Glock in a pool. The glock is a rugged 9mm pistol, and even glock does not recomend this.

I spent a considerable bit of time working with NSWC Crane on the OTB (Over The Beach) issues with M16's & frogmen.

First, you do NOT want to be in the water when a firearm is discharged underwater. It is no fun at all.

I had occasion to fully submerge more than one M16 rifle before loading & firing it. It always does enough damage to the weapon to render it inoperable. With some modifications, we were able to make it "safe" - but the weapon was still a paperweight until it made it back to the armory.

Below are some photos from the modified system. When the weapon fired, 19 cartridges were blown out the bottom of the magazine. The magazine latch was blown clear out of the lower receiver. The magazine well was bulged almost .200 at the widest point.

The extractor was bent by the flowing brass, and considerable force was required to move the bolt back out of the barrel extension due to the interference of the bent extractor.

The most important thing to note is the lack of any classic "pressure signs" on the primer. If you had fired that same round of M855 on a dry range the primer would have had the same little crater.

Shooting a submerged firearm is just a bad idea all around.





Have fun, stay safe.

B.

[runfiverun]

16"'s of water is kinda heavy compared to a 55 gr bullet.

[Molly]

> But I am a bit confused at the apparent discrepency in your hardness ratings. You should actually learn something of this if your going to make blanket statements as you have.

I'm willing. Educate me. But be aware that I have made no statement regarding the obturation (or lack thereof of any alloy or bullet except hard cast bullets. That specifically includes any statement regarding the performance of quenched bullets.

In your earlier note, you specified a 50/50 WW / lead alloy, and commented that it was quite soft. Now you rank that same composition as about 20 BHN. May I assume the difference is that some of them were quenched, and some were not? No, that can't be it: You specified that you needed a soft alloy to get obturation in your earlier note, and seem to be saying that you also get obturation when the same alloy is quenched for hardness. If that's so, your earlier comment that softness is necessary of obturation is rather confusing.

I note that you utterly failed to clarify this apparent discrepency.

>Again, there is a lot of data out there........ read some of it and learn whats going on....................What you assume through not knowing is confusing you.

If you want me to take you seriously, you need to be more specific. Exactly what have I said that your disagree with, and why? Why do you think that my knowledge (or lack thereof) of heat treating has any bearing on the results I obtained using non-heat treated bullets? It's hard for me to see the relevance.

Nonetheless, I am interested in what you say. Would you be willing to send me some of your bullets, as cast, as quenched, and as recovered? I would indeed like to examine them. I can send you a PM with my address if you are interested.

>When you've read the various sources on the web and have actually tried (instead of assuming) various alloys involving hardness, ductility, expansion, etc., then i'll discuss the situation with you. You need some better information than what you've had so far. Try here: http://www.lasc.us/CastBulletNotes.htm, various NRA publications authored by Dennis Marshall, this site and other various web sources. There is no substitute for actually trying something out yourself.[/QUOTE]

Hmmm. I don't find that a very satisfying response. I did indeed check out your reference, and it is an excellent source that I first came across some years back. However, it's been a while since I visited there, and I thank you for the reminder. I'll spend some time reviewing their offerings, and can recommend them to anyone interested. Do you have some particular offering you think I need to study?

Be aware that I have made no statement here that I have not personally tested and confirmed. I have been quite specific in describing what I did, the results I got, and the conclusions I drew from those results. Those results were repeatable, and formed a coherent pattern that varied with the alloy and pressure to provide a pretty complete picture of what really occurs in the bore. If you disagree with my intrepretation of those results, perhaps you could be a bit more specific about where you think I went wrong, and provide me with an alternative explanation that is consistent with the rest of the results.

Your participation has thus far consisted of complaints that I seem less competent than you are, but you seem unwilling to share much of your experience, describe your results, or the logic used to arrive at your conclusions. I am particularly annoyed at being called incompetent, without some description of what you consider my errors.

FYI, I corresponed with Dennis Marshall, did some alloy research with him, and have fired in competition with him. He didn't seem quite as contemptious of my knowledge of alloys as you are, and actually suggested that an alloy I designed be named after me. You can look it up in THE FOULING SHOT if you doubt my word.

I co-founded the Cast Bullet Association with Howard Thomas. You can also read of some of my own contributions in The Fouling Shot, including the "Technical Ramblings" column that I author. It seems quite popular, and to date, hasn't resulted in any complaints that i don't know what I'm talking about.

You can also read there (in the Fouling Shot) of my discovery and development of several previously unknown cast bullet technologies, including bore polishing (as opposed to fire lapping) and Cream of Wheat loads, which enables cast bullets to be shot without gas checks, lube or sizing. Phil Sharpe (a world renouned expert of earlier years) went on record as declaring that to be an absolute impossibility. But I did it. As far as I know, I'm the sole originator of the explanation of leading as a function of propellent gas etching, and explained why the old explanations of frictional rubbing and file-like abrasion from bore roughness were not valid.

But hey, I'm just an ignorant hick that knows nothing about cast bullets. I'm sure your own wisdom and achievements far outshine my own modest contributions. But perhaps you can discuss my errors and educate me, rather than just criticizing my explanations for what I've seen.

[Molly]

Quote:

OK kids, this thread has been entertaining, but it seems to have taken a dangerous turn.

Do NOT try shooting submerged firearms!

Yes, I am well aware of the fact that you can shoot a 9mm Glock in a pool. The glock is a rugged 9mm pistol, and even glock does not recomend this.

I spent a considerable bit of time working with NSWC Crane on the OTB (Over The Beach) issues with M16's & frogmen.

First, you do NOT want to be in the water when a firearm is discharged underwater. It is no fun at all.

I had occasion to fully submerge more than one M16 rifle before loading & firing it. It always does enough damage to the weapon to render it inoperable. With some modifications, we were able to make it "safe" - but the weapon was still a paperweight until it made it back to the armory.

Below are some photos from the modified system. When the weapon fired, 19 cartridges were blown out the bottom of the magazine. The magazine latch was blown clear out of the lower receiver. The magazine well was bulged almost .200 at the widest point.

The extractor was bent by the flowing brass, and considerable force was required to move the bolt back out of the barrel extension due to the interference of the bent extractor.

The most important thing to note is the lack of any classic "pressure signs" on the primer. If you had fired that same round of M855 on a dry range the primer would have had the same little crater.

Shooting a submerged firearm is just a bad idea all around.
Unquote

You make some good points, and actual experience is the most valid backing possible. Sounds like you have had plenty, and your cautions are sound.

But my own experience was under different circumstances and with different firearm mechanisms. I used bolt action rifles and a variety of revolvers. These do not present the autoloading mechanisms that were damaged in the tests you described. (Oh, and a .357 on a single shot Martini action too.) Almost all of my testing consisted of standing in the water (head out) and holding the gun underwater for firing. The exception was a single shot 22 RF, which I shot to annoy a few fish while fully underwater and using a face mask.

I was struck by two features of these tests: First, the great reduction in the intensity of the report. What would have normally been a sharp repoft (in air) was reduced to not much more than a 'thud' and a burble as the gas came up. I do not recall any shock wave that impressed me as hazardous if experienced when fully submerged. (This was many years ago, and most of my shooting (except with 22's) was with cast bullet loads that were well below full pressure. I do recall some exceptions with high prressure loads, but any unusual reports may have been forgotten. The lower pressure of most of my loads probably explains the difference between my experiences and your own.)

Secondly, I was struck by the fact that the projectiles did not even approximately follow a straight line through the water. Irregardless of caliber or pressure, they invariably described a sharply curved trajectory in the horizontal plane. Within a given load, this was consistent for each shot. I don't know, but I consider this to be a highly exaggerated expression of the trajectory drift that long range shooters experience, that is due to air turbulence based on the bullet rotation, much like a baseball curves due to air turbulence from the spinning ball. I thought it was rather neat.

[bohica2xo]

Molly, you may know a great deal about lead.

Your "underwater shooting" was a risky experiment.

The speed of the report is startling. It is the FIRST thing everyone noticed during testing.

The testing of bolt guns will reveal all sorts of failures, it really has nothing to do with the action of the M16. In fact, the gas venting through the bolt area reduces the pressure fast enough to prevent barrel bursts. I have blown up more than a few rifles - wet / dry, M40A1's to M60's. They all come apart if you screw up bad enough. I had to duplicate blowing the barrel clear out of an M2HB 50 cal once - it was not easy, but it can happen.

You "got away with it" using a revolver with (relatively) low pressure loads. The cylinder gap coupled with pressures below 20k would mitigate things rather well.

That in no way makes the idea a sound one, and I believe you should make an effort to caution against such testing outside of actual laboratory conditions.

Yes, the torque on the bullets makes them behave differently from the movie shots underwater.

B.

[Molly]

Molly, Your "underwater shooting" was a risky experiment.

The testing of bolt guns will reveal all sorts of failures, it really has nothing to do with the action of the M16.

You "got away with it" using a revolver with (relatively) low pressure loads. The cylinder gap coupled with pressures below 20k would mitigate things rather well.

That in no way makes the idea a sound one, and I believe you should make an effort to caution against such testing outside of actual laboratory conditions.

B.

Well, 'tis said that the Lord assigns special angels to watch over the affairs of fools and idiots, and that may well have been the case here too. I know for a fact that it has kept me safe from harm when by all rights I should have lost significant portions of my person.

But that being said, remember that revolvers were not my only tools: The bolt actions predominated, albiet at lower than normal pressures. It was the only way I had to recover fired bullets intact. A poor man has poor ways, as my father used to say.

I hope that the fact that I simply reported my own experience, and did not recommend the practice of shooting underwater will in some way mitigate my transgression. Should I ever discuss those experiences again, I will indeed include a strong cautionary note as you suggest.

I am quite interested in your confirmation that firing pin dents and overall priimer appearance did not reflect the theoretical and apparently very real pressure increase from the increased ejecta weight. This puzzled me at the time, and I still have no really good explanation for it. In my case, I thought it could have been that the lower pressure cast bullet loads simply had sufficient safety margin that the excursion wasn't enough to crater primers. At least that was my thought at the time, although some of the loads should have been hot enough to show some effect.

Now I have your report of a similar lack of apparent effect on primer appearance with full power factory ammo, despite obviously increased actual pressures from the increased ejecta weight. There can be no question of low pressure loads providing a margin in your tests, so my earlier thoughts were apparently groundless. (A single actual test trumps a thousand theoretical opinions!) Do you have any thoughts on the matter?

[bohica2xo]

Molly:

I could write a book about the pressure measurement mistakes in the firearms world. As is apparent in those pictures, the condition of a primer is not a clear indication of the actual pressure.

There are all sorts of things going on during ignition - it is far from being as simple as depicted in a reloading manual cartoon. I believe you have a chemistry background looking at your posts. Have you by chance read "The Chemistry of Powder & Explosives" by Tenney L Davis?

There are two big factors in the primer at the beginning. One is the Cv of the flash hole, and the second is the Brisance of the priming compound.

At the instant of ignition, there is substantial pressure within the chamber formed by the primer cup & pocket. The Cv of the flash hole control the peak pressure, and the duration. We have all seen the effect of firing only primers, or perhaps wax bullets in revolvers. The primer tends to back out of the case. The answer is to drill out the flash hole. Then the primer stays put.

Of course, we also know what happens if you load that drilled out case with a 357 mag load of 2400 behind a bullet & shoot it. The result looks like you accidentally swaped Red Dot for the 2400. It aint pretty.

The Cv of an orifice is very dependent on the differential pressure within the system. At firing, you detonate a small quantity of explosive. Primers detonate. A shock wave travels through the flash hole. If you are lighting a small quantity of fast burning powder on the other side, the pressure in the primer chamber may never even reach the peak it saw during detonation.

Now, if you are lighting a case full of 4831 in a 300 weatherby, things are different. Not only is the priming chamber exposed to the 55k peak chamber pressure, it is "held" under pressure much longer. This is why you will see primers with flow to the edges of the pocket, yet the firing pin dimple is ok, and it may not even be cratered.

This is one of the reasons that primer condition is not the best indicator of pressure. With say 5k psi in the priming chamber, it will take some time to pressureize it to 25k from the cartridge.

There is some speculation that the shockwave from detonation effectively occludes the flash hole for some period of time. If someone wants to spend 7 figures on this I am sure we can answer this question. One of my team believes very strongly that this is the reason for the primer condition in that failed case pictured. The theory is that pressures rise so fast that the case failed before the flash hole allowed enough gas to flatten the primer.

FYI, we did the underwater test on the M16 once with an 8 inch barrel stub with no gas hardware. The result was exactly as pictured. The bullet left the barrel on every weapon we blew up, regardless of barrel length.

Let's go back to the 300 weatherby for a minute. What happens if you try to hotrod it with faster powder, say IMR 4895? Primers look good @ 1 grain over max. @ 2 grains over max, the primer has a crater - but no edge flow. @ 4 grains over max, the primer is pierced, and the rifle re-cocked itself! But there is still less edge flow than the 4831 loads.

If you have been reloading for decades, you probably have noticed the changes in loading data. Copper crushers were repeatable, solid test tools. No engineer I ever met wanted to even try to translate the results into a "PSI" or worse, a "peak" pressure. They were just copper UNITS of pressure.

Piezoelectric strain gauges changed things. Now the peak pressure could be recorded, plotted & analyzed. Loading manuals became much more conservative. Go find a copy of the Speer #8 manual - and compare it to current loading specs.

I could go on all night, but the dogs expect me to get up in the morning & run with them. This old man is headed for bed.

B.

[Multigunner]

Yes, SOFT lead bullets will upset: the ordinary .22 rinfire is an excellent example. But again, I'm not talking about soft lead alloys. Dr Mann illustrated some massive upset in his book, but generally didn't mention hardness of the bullets. He DID get some jacketed bullets to upset, but I'll guarantee you they didn't upset in the throat. They upset because of muzzle blast, and I'm convinced that is the cause of most if not all base upset in hard bullets.

Any military range, and a lot of civilian ranges too, will let you find plenty of fired boattailed bullets in the backstop. You will find that they will invariably retain their streamlined shape in the base, which won't show the slightest evidence of upsetting in the throat, even though Dr. Mann 'demonstrated' that jacketed bullet bases will upset. Wonder why?

WWII rifles were sometimes manufctured with more attention to volume than quality. I once owned a supposedly 7x57 rifle whose bore was the correct diameter, but the rifling had been cut so deep that it would have fit a .30 caliber bullet. While useless for normal shooting, it serves as an excellent illustration of what I am talking about. Accuracy with 7x57 ammo was negligable, but digging out some fired bullets proved very educational: You could see where the engraving on the bullet was limited to the bore, simply because the bullet was too small to fill the grooves. The 'groove' portion of the bullet was (after wiping clean) still just as bright and shiny as before it was fired. Point is, that could not have occurred if the bullet base had upset in the throat as advertised. Ergo, the base of the bullet did NOT upset in the throat, and I don't give a BLEEP what Dr. Mann said.

I got rid of the rifle for the value of it's action because I was so annoyed at the poor accuracy. Sure wish I'd kept it now: I can think of about a dozen tests I'd like to run with it now. But if you want to follow up, try shooting 7.62 bullets in a .303 Brit, or something similar. I don't care if you shoot jacketed or cast. But if you can produce a bullet that shows an expanded base, you can give me the rasberry in public. But I'm not worried. I've been down that road and hit every pothole in it. And there wasn't an expanded base in any of them.

The .303 British Mk8 bullet (Mk8z amunition used single base nitro cellulose powders) is Boat Tailed, the original design used a step where the boat tail began to help seal and a similar boat tail bullet for long range match use with a cordite charge had a flange at that point which would expand to reduce blowby.
Boat tail bullets can upset very slightly due to pure inertia of the lead core, but the Mk8 bullet was infamous for allowing excessive blowby when fired from even a slightly eroded Enfield bore. The small opening at the base did not allow the normal amount of upset that all open flat base FMJ .303 bullets relied on for proper sealing in the more often than not oversized Enfield bores.
Inaccuracy of the Mk8 bullet when fired in Enfield rifles which show any noticable throat erosion is a long recognized situation, precisely because it doesn't upset as it should.
Cordite also eats away the bottom of the grooves faster than the lands, which increases the problem of blow by when the bore is significantly eroded by gas.

Single base powders used by the MkVIIz ammunition did not erode bores as quickly, but due to the lack of the initial thrust provided by the cordite charge of the standard MkVII ammunition the bullets of the MkVIIz often don't upset enough to prevent blowby.

I've fired salvaged bullets from old .30-30 Winchester ammo in several Enfield rifles with excellent accuracy. The .30-30 bullets being constructed for a much lower pressure range upset nicely into the throat and grooves of bores .005 or more larger than the bullets. Being a closed base with soft core and jacket the .30-30 bullets need not expand at the base itself in order to expand the body of the bullet to fill the throat and grooves. Rather than expanding by the action of high pressure gas on an exposed lead core at the base, inertia of the core results in the molecules of the lead being jammed together as the rear of the bullet is pushed forwards before the impulse is fully transmitted to the rest of the core, forcing the jacket outwards and into the grooves.
A number of the early smokeless powder rifles relied on bullet upset to fill the throat and grooves, without such upset the rifles would not have had a useable degree of accuracy.
Powders used back then were often a double base type with significant initial thrust. When the US military went with the single base pyrocellulose and MR powders they found that the previous loose allowable tolerances of bores did not allow optimum accuracy, since the single base powders did not provide sufficient initial thrust. At about the same time the Ordnance dept ordered increased thickness of jackets and alloying of the lead cores to avoid the blowing through of bullet jackets over heated by blowby gases in eroded bores.

As of the present day bores and bullets are usually closely matched in diameters, so bullets specifically designed to hold up under high velocity impacts need not rely on upset for accuracy. At the same time this makes severe throat erosion more destructive to accuracy.

So if a bullet specifically designed to function without upset shows no sign of upset thats really no suprize. If a bullet has upset to fill the throat, then traveled the length of the bore being swaged down to fit the bore diameter then how would you expect to measure any upset on the spent bullet.

As for your oversized Mauser bore, if it was that far out of spec there would not have been a good enough seal to begin with for pressure to slug out the bullet, much of the initial thrust having been lost as pure blowby.

Picking examples where the process of bullet upset can not be expected to operate properly does not preclude the fact that bullet upset is a known factor and was, and to some extent still is, relied on for best performance.

A recognized phenomena is the constriction of the bore ahead of the throat due to carbon infiltration of alligator heat cracking of the surface.
When a well worn match grade barrel is shortened at the breech, rethreaded and rechambered, this sets the constricted portion back just far enough that its still within the zone of initial thrust, the bullet now can recover from the slight constriction and undergo a secondary bumping up to once more fill out the grooves. Set back and rechambered match barrels are often more accurate than a new barrel due to a gentle taper bore effect from mechanical erosion.
The choice of many pre WW2 target shooters to use the highly erosive HiVel powders (which often burned out the throat within 400 rounds) may have been due to its high nitroglycerin content providing a much longer bumping up zone than less erosive single base powders. A eroded barrel could then be set back and rechambered several times.

[Molly]

Hi Multigunner,

I can't tell you what a delight your posting is! It is SO seldom that I get a chance to discuss firearms with someone who seems to know what they are talking about!

>The .303 British Mk8 bullet (Mk8z amunition used single base nitro cellulose powders) is Boat Tailed, the original design used a step where the boat tail began to help seal and a similar boat tail bullet for long range match use with a cordite charge had a flange at that point which would expand to reduce blowby.

My own testing and conclustions are limited to cast bullets for the most part. I have done NO testing with jacketed bullets, but being reasonably observant, I notice that I see little evidence of obturation of jacketed bullets found on the backstop. How can a boat tail - particularly a stepped design - help obturation over what might be obtained with a plain based bullet?

>Boat tail bullets can upset very slightly due to pure inertia of the lead core, but the Mk8 bullet was infamous for allowing excessive blowby when fired from even a slightly eroded Enfield bore. The small opening at the base did not allow the normal amount of upset that all open flat base FMJ .303 bullets relied on for proper sealing in the more often than not oversized Enfield bores.

>Inaccuracy of the Mk8 bullet when fired in Enfield rifles which show any noticable throat erosion is a long recognized situation, precisely because it doesn't upset as it should. Cordite also eats away the bottom of the grooves faster than the lands, which increases the problem of blow by when the bore is significantly eroded by gas.

I am not only not an expert on british munitions, I know little more than that they mostly used cordite propellent. But doesn't your report here argue against upset and obturtion, if the bullet was unable to upset enough to fill even slight bore enlargement? Also, it is my understanding that the reason for the erosive reputation of cordite was precicely because of the lack of obturation: The propellent gas was channeled through the unfilled grooves, resulting in what is generally referred to a 'gas cutting'.

>Single base powders used by the MkVIIz ammunition did not erode bores as quickly, but due to the lack of the initial thrust provided by the cordite charge of the standard MkVII ammunition the bullets of the MkVIIz often don't upset enough to prevent blowby.

Now there's an interesting observation! If single base powders failed to produce consistent obturation as you say, why then did they not produce severe erosion from gas cutting?

>I've fired salvaged bullets from old .30-30 Winchester ammo in several Enfield rifles with excellent accuracy. The .30-30 bullets being constructed for a much lower pressure range upset nicely into the throat and grooves of bores .005 or more larger than the bullets. Being a closed base with soft core and jacket the .30-30 bullets need not expand at the base itself in order to expand the body of the bullet to fill the throat and grooves. Rather than expanding by the action of high pressure gas on an exposed lead core at the base, inertia of the core results in the molecules of the lead being jammed together as the rear of the bullet is pushed forwards before the impulse is fully transmitted to the rest of the core, forcing the jacket outwards and into the grooves.

But are you not thus arguing that base obturation does not occur (at least in this example), and thus agreeing with my own conclusions? Upset of the body of the bullet is not the same as upset of the base, which is the foundation of the discussion here. (I can believe that the body of a bullet can upset under some conditions, and can cite similar reports. But I think your citation here supports my arguement against upset ofthe bullet base.)

>A number of the early smokeless powder rifles relied on bullet upset to fill the throat and grooves, without such upset the rifles would not have had a useable degree of accuracy.

Agreed, but those rifles generally used very soft lead bullets, and usually with a paper patch. My arguement has been based around the bases of hard bullets.

>Powders used back then were often a double base type with significant initial thrust. When the US military went with the single base pyrocellulose and MR powders they found that the previous loose allowable tolerances of bores did not allow optimum accuracy, since the single base powders did not provide sufficient initial thrust. At about the same time the Ordnance dept ordered increased thickness of jackets and alloying of the lead cores to avoid the blowing through of bullet jackets over heated by blowby gases in eroded bores.

Can't really coment here, except to note that a Krag with a bore below 0.311 is unusual, and I've never seen one with a 0.308 bore.

>As of the present day bores and bullets are usually closely matched in diameters, so bullets specifically designed to hold up under high velocity impacts need not rely on upset for accuracy. At the same time this makes severe throat erosion more destructive to accuracy.

Accuracy per se wasn't an important criteria for most of my testing. I'm not a match shooter. 1.5 or 2 inch groups fill my needs quite well.

>So if a bullet specifically designed to function without upset shows no sign of upset thats really no suprize.

Agreed. Although I was and am not aware that modern jacketed bullets are especially designed to prevent obturation.

>If a bullet has upset to fill the throat, then traveled the length of the bore being swaged down to fit the bore diameter then how would you expect to measure any upset on the spent bullet.

That's almost a direct quote from my earlier postings, explaining why Dr. Mann's photos of grossly expanded bullet bases could not possibly have been produced in the rifle throat. However, if a bullet is designed with grease grooves and a gas check shank, you could reasonably expect to find them at least partially obliterated by throat expansion followed by resizing into the bore. Even the lowly .22 RF base provides ample and convincing evidence of such expansion and resizing. But I see no evidene of it on recovered hard cast bullets.

>Picking examples where the process of bullet upset can not be expected to operate properly does not preclude the fact that bullet upset is a known factor and was, and to some extent still is, relied on for best performance.

Now that has me confused. Unless you speak of very minimal throat upset indeed, you seem to be saying that modern bullets are designed to prevent upset, and thus produce sub-optimal performance.

>A recognized phenomena is the constriction of the bore ahead of the throat due to carbon infiltration of alligator heat cracking of the surface.

Ummm. Minor semantic quibble if I may: The infiltration of carbon into the bore surface raises the carbon concentration, resulting in a surface that in imbrittled after it has been cooled by the rest of the barrel. This embrittlement results in micro-cracking of the bore surface when it is expanded by the subsequent shot. Continued shooting provides more carbon inflitration, which increases and deepens the cracking until microscopic flakes seperate from the brittle surface, and produces an eroded condition. The generation of a brittle surface in the process of spalling flakes isn't really a constriction per se, but the elevation of flake edges as it curls from embrittlement might produce something like a very slight but very irregular constriction.

Thanks again for your feedback. Hope you can find time to answer some of my questions. But feel free to pick and choose points to discuss in any reply you may wish to make, to keep the volume of the correspondence to a reasonable level.

[Multigunner]

But are you not thus arguing that base obturation does not occur (at least in this example), and thus agreeing with my own conclusions? Upset of the body of the bullet is not the same as upset of the base, which is the foundation of the discussion here. (I can believe that the body of a bullet can upset under some conditions, and can cite similar reports. But I think your citation here supports my arguement against upset ofthe bullet base.)

You seem to be shoveling all bullets into a pigeonhole here. The instance of a grossly undersized bullet with thin jacket and soft core upsetting in the body due to inertia is an example of upsetting being not entirely dependent on gas pressure against a soft base. It illustrates that different mechanics can produce the same result, the filling out of the throat and grooves.

>A number of the early smokeless powder rifles relied on bullet upset to fill the throat and grooves, without such upset the rifles would not have had a useable degree of accuracy.

Agreed, but those rifles generally used very soft lead bullets, and usually with a paper patch. My arguement has been based around the bases of hard bullets.

The original 8mm J bore rifles such as the GEW88 used a .318 bullet in a .321 bore, the bullet was jacketed with lead core open at the base. The purpose was to avoid excessive pressures in heavily fouled bores, the bullet bumping up to fill out the bore rather than being swaged down to fit.

As powder operating temperatures rose, the Cordite Mk1 with 58% nitroglycerine approaching 5,000 degrees use of lead bullets was feasible only with light loaded pistol cartridges which used a relatively tiny charge of flaked cordite.
When .303 cartridges were tested for possible dangers of firing with water, oil or gease in the bore it was found that when a small amount of grease was at the case mouth the velocity increased very slightly along with a noticeable rize in pressures. The conclusion was that the grease formed a momentary incompressible seal which prevented release of gas around the bullet base during the micro second it took for the bullet to bump up to fill the throat.

The .30-40 Krag originally used several types of very energetic and highly erosive powders similar to cordite, and cordite itself at one point in development.
The energetic powder coupled with a soft core and flexible jacket allowed the bullet to bump up just as the .303 did.

Tolerances of mass produced barrels and bullets were fairly loose compared to later years, and theres a limit to how much bullet upset can make up for a loose bullet to bore fit. Blowby could be all but eliminated when the barrel was new but sooner or later it would set in and erosion would increase at an accelerating rate.
A bore eroded by Cordite could remain accurate for a time so long as only cordite ammunition was used, because the cordite was energetic enough to bump up the bullets.

As pressures and velocities increased, the 1903 220 grain bullet load using a double base powder was found to overheat jackets when any noticable erosion occured greatly shortening bore life. Single base powders were then adopted for the 150 gr .30/06 higher velocity load, bullet and bore size then had to be matched near perfectly. Reduced thermal erosion allowed use of a harder jacket and upset was minimal.

As for more modern harder jacketed bullets, terminal performance at much higher velocities require that the bullet be less prone to deformation, and in the case of AP ammunition the core is a very solid steel or alloy with no elasticity at all, only a thin lead sheath between core and jacket cushioning the bullet to prevent excessive friction and allow the jacket to fill out the grooves by a swaging action. The lead sheath being trapped between jacket and core it gives in the only open path of least resistence left to it, pushing the jacket deeper into the grooves.

If you cast a bullet of alloy too hard to allow upset with the powder type and charge weight used then it will fail to upset, thats obvious.
If the bullet is designed from jump to obturate , such as the heel based Colt .38 Long then you will have efficient obturation, without which no accuracy would have been possible.
Some cartridge/firearms combinations are designed specifically to rely on upset while others are not, theres no one size fits all answer to your question.
If you use an undersized bullet cast of a too hard alloy and propel it by means of a powder charge that does not provide sufficient initial thrust to bump up the bullet then it won't seal properly and may skid in the rifling, accuracy would be poor under such conditions, and velocity inconsistent.

If bullet diameter is the same or greater than bore diameter, upset is far less of a factor, but some upset is beneficial in allowing better engraving of rifling to bullet, and when carbon infiltration of the heat check gator cracking is severe a longer energetic impulse can compensate.
Constrictions due to carbon infiltration are usually found about three to four inches further down bore from the throat. Erosion of the throat itself is much like you describe.

Ummm. Minor semantic quibble if I may: The infiltration of carbon into the bore surface raises the carbon concentration, resulting in a surface that in imbrittled after it has been cooled by the rest of the barrel. This embrittlement results in micro-cracking of the bore surface when it is expanded by the subsequent shot. Continued shooting provides more carbon inflitration, which increases and deepens the cracking until microscopic flakes seperate from the brittle surface, and produces an eroded condition. The generation of a brittle surface in the process of spalling flakes isn't really a constriction per se, but the elevation of flake edges as it curls from embrittlement might produce something like a very slight but very irregular constriction.

But further down bore the carbon is pushed under the edges raising them then bracing the raised area, metalic fouling contributes creating an aggregate that can be harder and more wear resistent than the steel itself and nearly impossible to remove even by lapping. The carbon seals the atomised metal fouling from copper solvents and the metal in turn protects the carbon from effective removal by carbon solvents. The composite surface at that point being far harder than a bronze brush or bore polishing compounds that would not wear away steel as well as the hardened fouling.

[Molly]

Hi Multigunner,

>You seem to be shoveling all bullets into a pigeonhole here. The instance of a grossly undersized bullet with thin jacket and soft core upsetting in the body due to inertia is an example of upsetting being not entirely dependent on gas pressure against a soft base. It illustrates that different mechanics can produce the same result, the filling out of the throat and grooves.

Umm, this is getting a bit hard to follow, but I don't think I am. I'm distinguishing between hard alloy bullets (which I do not believe upset ANYWHERE) and jacketed bullets with a pure or nearly pure lead core (that I don't see much evidence of upsetting with either) that (if iI understand you correctly) you feel can upset either at the base or midway along its length.

Although I don't see any evidence of jacketed upset, I can see how it might occur with a thin, soft jacket and a very soft core. I'm willing to take your word on this one, and revise my position to say that while some jacketed bullets may obturate, it is only to a slight degree at most. I base this on our common position that no bullet can expand very much in the throat due to support of the barrel limiting the expansion.

>As powder operating temperatures rose, the Cordite Mk1 with 58% nitroglycerine approaching 5,000 degrees use of lead bullets was feasible only with light loaded pistol cartridges which used a relatively tiny charge of flaked cordite.
>When .303 cartridges were tested for possible dangers of firing with water, oil or gease in the bore it was found that when a small amount of grease was at the case mouth the velocity increased very slightly along with a noticeable rize in pressures. The conclusion was that the grease formed a momentary incompressible seal which prevented release of gas around the bullet base during the micro second it took for the bullet to bump up to fill the throat.

I've heard a slightly different explanation of this: The version I heard attributed the elevated pressures to the incomprssable grease preventing or at least delaying the normal bullet release, allowing pressure to increase behind it rather sharply. This was also the explanation of the US Army for the blown up match rifles for several years at Camp Perry. The cupronickle bullet jackets would foul bores very rapidly and badly when shot 'bare'. Shooters recalled the use of grease to avoid fouling with cast bullets, and decided the same remedy would work with jacketed bullets too. They would smear MobilLube grease all over the front of the cartridge before going to the firing line. Pressures skyrocketed, and actions cracked. I think 'Hatchers Notebook' contains a pretty detailed report.

>Tolerances of mass produced barrels and bullets were fairly loose compared to later years, and theres a limit to how much bullet upset can make up for a loose bullet to bore fit. Blowby could be all but eliminated when the barrel was new but sooner or later it would set in and erosion would increase at an accelerating rate.
>A bore eroded by Cordite could remain accurate for a time so long as only cordite ammunition was used, because the cordite was energetic enough to bump up the bullets.

This makes a certain amount of sence, given what you've reported here. It's logical, and I don't know of anything to contradict it. My own conclusions about jacketed bullets not obturating were based on jacketed bullets recovered from the berm of a military range, not on a detailed research program like I used for hard cast bullets. Some of them looked like they could be reloaded and fired again. Hmmm. That triggered a recollection of a long ago article in the Rifleman, which reported that a Scandinavian marksman set up his winter range to use heavy snow drifts to backstop his bullets. Come spring, he went over the area of the drift and recovered his bullets, and actually did reload and shoot them again. I have no idea of the hardness of his bullet jackets, but any obturation had to be very slight indeed.

>As pressures and velocities increased, the 1903 220 grain bullet load using a double base powder was found to overheat jackets when any noticable erosion occured greatly shortening bore life. Single base powders were then adopted for the 150 gr .30/06 higher velocity load, bullet and bore size then had to be matched near perfectly. Reduced thermal erosion allowed use of a harder jacket and upset was minimal.

OK, this probably represents what I picked up and inspected on the base range. Many of the jackets obviously did not fill out the grooves, and exhibited no sign of friction or abrasion except on the lands.

>If you cast a bullet of alloy too hard to allow upset with the powder type and charge weight used then it will fail to upset, thats obvious.

OK, let me specify that I have not been able to find any evidence of obturation of hard alloy cast bullets with any load or pressure that provides sufficient accuracy to enable fired bullets to be found and recovered. I suppose it's possible that some upset may occur with high pressure that produces very wild shooting. Hmm. No, I've loaded to some pretty scary pressures using powders like 2400 or 4227, trying to produce base upset. I don't recall noticing any obturqtion from these loads.

>If the bullet is designed from jump to obturate , such as the heel based Colt .38 Long then you will have efficient obturation, without which no accuracy would have been possible.

Yes, and the HB 38 target loads as well, not to mention the 32 long Colt and Minne balls, and a few others as well. But again, these invariably used the softest lead possible to obtain.

>If bullet diameter is the same or greater than bore diameter, upset is far less of a factor, but some upset is beneficial in allowing better engraving of rifling to bullet, and when carbon infiltration of the heat check gator cracking is severe a longer energetic impulse can compensate.

OK, I'll take your word on this one. I have no way to test duration of my internal ballistics. But I don't see why a 0.312 bullet needs to upset to fill the bore, and produce better engraving from a 0.308 bore.

>Constrictions due to carbon infiltration are usually found about three to four inches further down bore from the throat. Erosion of the throat itself is much like you describe.
>But further down bore the carbon is pushed under the edges raising them then bracing the raised area, metalic fouling contributes creating an aggregate that can be harder and more wear resistent than the steel itself and nearly impossible to remove even by lapping. The carbon seals the atomised metal fouling from copper solvents and the metal in turn protects the carbon from effective removal by carbon solvents. The composite surface at that point being far harder than a bronze brush or bore polishing compounds that would not wear away steel as well as the hardened fouling.

I think you are describing something that may occur exclusively with jacketed bullets, which I almost never use. I have never managed to generate either throat erosion (which I have watched for) or the carbon / jacket fouling constriction you describe above in any gun I have owned, and some of them have seen quite a bit of shooting. I particularly have in mind a Garand that endured many years of regular use of hard cast bullets with sufficient power to operate the mechanism very effectively, and when I sold it, the barrel stilll looked new inside. I have also had similar results from a variety of milsurp autoloaders, though the Garand saw the greatest use by far.

Speculation might suggest that contamination of the bore by bullet lube may have been adequate to protect the bore from any erosion, but it could also be logicly argued that the presence of organic material (lube) would have increased the carbon availability and exacerbated the erosion. I lean toward the former, having seen no evidence of erosion in any of my guns.

[45 2.1]

But I am a bit confused at the apparent discrepency in your hardness ratings. You should actually learn something of this if your going to make blanket statements as you have.

I'm willing. Educate me. But be aware that I have made no statement regarding the obturation (or lack thereof of any alloy or bullet except hard cast bullets. Just what exactly do you define as a hard boolit? Two boolits can hardness test at 25 BHN..... one there strictly by alloy components, the other with very little antimony there by heat treating. Both have entirely different properties other than hardness. That specifically includes any statement regarding the performance of quenched bullets.

In your earlier note, you specified a 50/50 WW / lead alloy, and commented that it was quite soft. Now you rank that same composition as about 20 BHN. May I assume the difference is that some of them were quenched, and some were not? The proper term is heat treated.... several methods are available to do that also. No, that can't be it: You specified that you needed a soft alloy to get obturation in your earlier note, and seem to be saying that you also get obturation when the same alloy is quenched for hardness. If that's so, your earlier comment that softness is necessary of obturation is rather confusing. Your a real card........ I can see you've only dealt with high antimony alloys. Most of the information out there only deals with them also...... those alloys produce a non-ductile hard boolit. There are ways to negate that. Those have been discussed here on this board for quite some time. I see you are not aware of them.

I note that you utterly failed to clarify this apparent discrepency.

>Again, there is a lot of data out there........ read some of it and learn whats going on....................What you assume through not knowing is confusing you.

If you want me to take you seriously, you need to be more specific. Why, I have no wish for my information to be your next article. Many things talked about here have been the subject of your articles in the "Fouling Shot" as well as several places. Exactly what have I said that your disagree with, and why? Why do you think that my knowledge (or lack thereof) of heat treating has any bearing on the results I obtained using non-heat treated bullets? It's hard for me to see the relevance. It all depends whether you want a hard boolit that acts: (1) as a solid or one that (2) acts like a softpoint. Alloying with traditional elements to get a hard alloy is "old" technology now and quite limiting as to what you can achieve.

Nonetheless, I am interested in what you say. Would you be willing to send me some of your bullets, as cast, as quenched, and as recovered? I would indeed like to examine them. I can send you a PM with my address if you are interested.

>When you've read the various sources on the web and have actually tried (instead of assuming) various alloys involving hardness, ductility, expansion, etc., then i'll discuss the situation with you. You need some better information than what you've had so far. Try here: http://www.lasc.us/CastBulletNotes.htm, various NRA publications authored by Dennis Marshall, this site and other various web sources. There is no substitute for actually trying something out yourself.[/QUOTE]

Hmmm. I don't find that a very satisfying response. It was meant to allow you to do some homework and get yourself up to speed, only so far as the articles are advanced though. I did indeed check out your reference, and it is an excellent source that I first came across some years back. However, it's been a while since I visited there, and I thank you for the reminder. I'll spend some time reviewing their offerings, and can recommend them to anyone interested. Do you have some particular offering you think I need to study? Yes........ I can highly recommend you do some of your own tests with alloys other than what you know about. Ones with much reduced alloy constituents would be a good course of study. They act much differently than what you know about.

Be aware that I have made no statement here that I have not personally tested and confirmed. I have been quite specific in describing what I did, the results I got, and the conclusions I drew from those results. Those results were repeatable, and formed a coherent pattern that varied with the alloy and pressure to provide a pretty complete picture of what really occurs in the bore. If you disagree with my intrepretation of those results, perhaps you could be a bit more specific about where you think I went wrong, and provide me with an alternative explanation that is consistent with the rest of the results.

Your participation has thus far consisted of complaints that I seem less competent than you are, but you seem unwilling to share much of your experience, describe your results, or the logic used to arrive at your conclusions. I am particularly annoyed at being called incompetent, without some description of what you consider my errors. Almost all of these things are detailed in the archives here. I don't have the need to publish what i've done, though quite a few want me to write a book on the subject.

FYI, I corresponed with Dennis Marshall, did some alloy research with him, and have fired in competition with him. He didn't seem quite as contemptious of my knowledge of alloys as you are, and actually suggested that an alloy I designed be named after me. You can look it up in THE FOULING SHOT if you doubt my word.

I co-founded the Cast Bullet Association with Howard Thomas. You can also read of some of my own contributions in The Fouling Shot, including the "Technical Ramblings" column that I author. It seems quite popular, and to date, hasn't resulted in any complaints that i don't know what I'm talking about.

You can also read there (in the Fouling Shot) of my discovery and development of several previously unknown cast bullet technologies, including bore polishing (as opposed to fire lapping) and Cream of Wheat loads, which enables cast bullets to be shot without gas checks, lube or sizing. The black powder and early smokeless eras did this also, a minimum of 110 years ago. Try reading what Dr. Hudson did. Phil Sharpe (a world renouned expert of earlier years) went on record as declaring that to be an absolute impossibility. But I did it. As far as I know, I'm the sole originator of the explanation of leading as a function of propellent gas etching, and explained why the old explanations of frictional rubbing and file-like abrasion from bore roughness were not valid.
A lot of these items were in print before you were born. Not much is new, just rediscovered from time to time..... sometimes from generation to generation.

But hey, I'm just an ignorant hick that knows nothing about cast bullets. I'm sure your own wisdom and achievements far outshine my own modest contributions. But perhaps you can discuss my errors and educate me, rather than just criticizing my explanations for what I've seen. I've read your stuff in several places. I've known who you are for quite awhile also. Remember that there is no substitute for doing something yourself.... try it out.

[Molly]

45 2.1
>You should actually learn something of this if your going to make blanket statements as you have.

The only 'blanket statements' I am aware of making are factual descriptions of my observations, what I have done, the results I obtained, and the theoretical explanations I have developed for them.

> Just what exactly do you define as a hard boolit? Two boolits can hardness test at 25 BHN..... one there strictly by alloy components, the other with very little antimony there by heat treating. Both have entirely different properties other than hardness.

And I was quite specific that my reports and work applied only to what you describe as high antimony alloys, ranging from wheelweights through linotype to monotype. You may be correct that quenched low antimony alloys can have equal hardness but differ radically in other properties. But it seems unreasonable to take me to task because you don't think my results apply to an area outside what I have defined as their domain.

In your earlier note, you specified a 50/50 WW / lead alloy, and commented that it was quite soft. Now you rank that same composition as about 20 BHN.
>Your a real card........ I can see you've only dealt with high antimony alloys. Most of the information out there only deals with them also...... those alloys produce a non-ductile hard boolit. There are ways to negate that. Those have been discussed here on this board for quite some time. I see you are not aware of them.

I note that you utterly failed to clarify this apparent discrepency.

>Again, there is a lot of data out there........ read some of it and learn whats going on....................What you assume through not knowing is confusing you.

I don't see that I assume anything. You assume that my results are intended to apply in areas that are well outside their sharply defined domain. Your assumptions are your own responsibility. I will stand by what I have said.

>Why, I have no wish for my information to be your next article. Many things talked about here have been the subject of your articles in the "Fouling Shot" as well as several places.

... And now you accuse me of intending plagarism. It is true that I considered a few conversations here to be of more general interest, and passed them along to others AFTER ASKING AND RECEIVING PERMISSION TO DO SO FROM THE OTHER PARTICIPANTS. I assure you that 'your information' will have to be a great deal more specific and detailed than 'go look it up' before it will interest anyone. May I invite you to submit your skills and knowledge to peer review by sending a few articles to the Fouling Shot for their consideration? Surely someone of your skill and wisdom should receive the recognition he deserves.

>It all depends whether you want a hard boolit that acts: (1) as a solid or one that (2) acts like a softpoint. Alloying with traditional elements to get a hard alloy is "old" technology now and quite limiting as to what you can achieve.

Yes, hard alloys is now considered 'old technology' by some. But in no way does that detract from its validity or usefulness. And your 'new technology' of quenching (which is nearly as old) has yet to garner the adherents or admirers that the 'old technology' still retains. My personal explanation for this is the difficulty of obtaining consistent results without knowledge of the alloy composition ... a wisdom you seem to denegrate as you laud the quenching process it depends on.

Nonetheless, I am interested in what you say. Would you be willing to send me some of your bullets, as cast, as quenched, and as recovered? I would indeed like to examine them. I can send you a PM with my address if you are interested.

>Yes........ I can highly recommend you do some of your own tests with alloys other than what you know about. Ones with much reduced alloy constituents would be a good course of study. They act much differently than what you know about.

I find it fascinating that after decades of conducting my own tests that you would recommend I consider adopting the practice. I do not need to test softer alloys in order to validate the results I have obtained and consistently reproduced with hard alloys.

Your participation has continues to consist of complaints that I am less competent than you are, but you continue unwilling to share much of your experience, describe your results, or the logic used to arrive at your conclusions. You seem incapable of justifying your criticisms with specific valid objections to the accuracy and truthfulness of what I claim. If you have them, let's hear them. Otherwise, I grow weary of responding to hot air without the recompense of having my errors corrected. And I do not consider that complaining that my results don't apply well to something I never tested or claimed to test as a valid or specific objection.

>Almost all of these things are detailed in the archives here. I don't have the need to publish what i've done, though quite a few want me to write a book on the subject.

I would also encourage you to do so.

> The black powder and early smokeless eras did this also, a minimum of 110 years ago. Try reading what Dr. Hudson did.

My own readings of these eras recount immense effort dedicated to overcoming problems of bare lead fouling the bore with lead deposits from unpatched bullets, and with the heavy fouling of black powder. If you know of anyone who succeeded in understanding and overcoming them before me, let's hear it - and again, some specifics please!

A lot of these items were in print before you were born. Not much is new, just rediscovered from time to time..... sometimes from generation to generation.

Again, some specifics please. I recommend your criticism of blanket statements for your own consideration.

>I've read your stuff in several places. I've known who you are for quite awhile also. Remember that there is no substitute for doing something yourself.... try it out. [/QUOTE]

Mr 45 2.1, NOBODY can be a complete expert in every possible phase of cast bullet expertese. The many fields are simply too broad and complex. I take considerable care to avoid claiming skills or experience that I don't have. What I say can be taken to the bank. But don't put words in my mouth. I have REPEATEDLY limited the applicability of my reports to the hard, high antimony alloys I worked with, and find your complaints that they don't apply to ductille quenched alloys rather offensive, especially when you seem to be incapable of pointing out a single error in anything I have said.

Now you have the right of freedom of speech to say anything that isn't libelous or slanderous. But I have the right to require that my correspondence repay the effort by either teaching me something new or by allowing me the gratification of helping another. Your approach seems analgous to telling a first grader to become a brain surgeon by studying. The advice may be sound in principle, but does not seem very useful. Try being helpful. You will find it quite gratifying.

[45 2.1]

Mr 45 2.1, NOBODY can be a complete expert in every possible phase of cast bullet expertese. We were talking about hard boolits, obtainable thru several venues. Not every possible phase of cast boolit expertese. The many fields are simply too broad and complex. I take considerable care to avoid claiming skills or experience that I don't have. Thus the reason to read and study what is out there so you can learn more. What I say can be taken to the bank. But don't put words in my mouth. I have REPEATEDLY limited the applicability of my reports to the hard, high antimony alloys I worked with That revelation has been covered for many years by a lot of people and has no surprises., and find your complaints that they don't apply to ductille quenched alloys rather offensive Find it however you want, but there are several other ways to improve greatly on the old high antimonial alloys. Just why do we want a cast boolit to behave like a solid (unless you do want a solid which is brittle and shatters upon contact with solid material) when there are other ways to get there without the brittle nature your talking about., especially when you seem to be incapable of pointing out a single error in anything I have said. I could do that, but you might not like what was said. Besides, like I said, i'm not going to be the source of your next article.

Now you have the right of freedom of speech to say anything that isn't libelous or slanderous. But I have the right to require that my correspondence repay the effort by either teaching me something new or by allowing me the gratification of helping another. You indeed have the right to pass along what you've experienced, but others have done that quite well before..... I have no requirement to teach you anything, but will tell you there are other better ways of doing things. I could suggest a course of action that would show you what can be done, that is provided you would follow it to the end. Your approach seems analgous to telling a first grader to become a brain surgeon by studying. Which the first grader could do provided he went through the various grades, high school, college, medical school, residency etc. till he achieved that goal. Takes time and effort on the part of the first grader......... doesn't it. Thus the push for you to read something about alloys other than what you know. Without some base reference, anything I have to tell you wouldn't make too much sense to you since it seems to be a foriegn concept to you. The advice may be sound in principle, but does not seem very useful. Try being helpful. You will find it quite gratifying. I am, as several others could attest to, being helpfull............ you just don't perceive it that way.

[Molly]

B]I am, as several others could attest to, being helpfull............ you just don't perceive it that way.[/B]

Well sir, it seems that we have reached an area of agreement.

Goodby.

[Multigunner]

Well Molly the reasons why conclusions on the mechanism by which the lubricated match bullets caused action failures of the Springfields aren't quite the same as those in which grease caused only a slight increase in velocity and noticable rise in pressure of the .303 are because the design philosophy and stage of development, plus the maximum chamber pressures of these cartridges and their platforms are far more different than you might think. Remember that the Lee Enfields were built to far looser tolerances and the chamber pressures were far lower. The throat of the Springfield was a tighter fit and bullets were a close match to bore size. The pressure curve of the propelants was also different.

As for Mann's conclusions, I found a PDF of his work and his reasoning is very straight forwards and easily understood. Perhaps you should read it again.

Now as for a bullet of .312 in a .308 bore, its likely that bumping up would have little benefit other than to insure that the bullet did not skid in the rifling allowing gas to leak past the corners of the portion of the surface in the grooves.
The most modern long range target and snip rifle bores use grooves cut with a radius at the corners, a sharp angle there can allow gas to blowby, and any skidding in the grooves can greatly increase the problem. Some skidding is unavoidable as the bullet is first engraved at origin of rifling even if the bullet is oversized, but pressures are high enough that the material of jacket or lead body are still pressed deep enough to fill out the groove.

Instances of skidding and its effects can be illustrated by the example of a .22 bullet known to have been fired from a certain rifle not being matched to the rifle by foresic examination. In that instance excessive grease in the bore coupled with the low pressure of the cartridge allowed the copper washed bullet to skid leaving the engraving of the lands far wider than normal, a lead bullet fired in the same barrel without grease filled out the grooves and prevented skidding.
When the first Short Magazine Lee Enfields were produced they used the same MkVI cartridge as the earlier Lee Enfields, to maintain the same muzzle velocity from the 25 inch barrel of the SMLE MkI as from the LE rifle with its much longer barrel , the last fourteen inches of the bore was lapped in a reverse taper to relieve bullet friction. This appears to have worked in so far as the velocity was concerned but this also allowed blowby and the bullets which had been well engraved during the first 9 inches of travel were not able to upset enough to fill out the increased diameter further down bore, the bullets heated and skidded, the amount of skid increasing the further down bore it traveled. Accuracy was adversely affected. The reverse taper barrel was not used after the Mk1 and those Mk1 barrels were ordered replaced by 1917 with conventional barrels. No doubt the order would have gone out sooner if War had not made pulling these off the line difficult.

I have never managed to generate either throat erosion (which I have watched for) or the carbon / jacket fouling constriction you describe above in any gun I have owned, and some of them have seen quite a bit of shooting. I particularly have in mind a Garand that endured many years of regular use of hard cast bullets with sufficient power to operate the mechanism very effectively, and when I sold it, the barrel stilll looked new inside. I have also had similar results from a variety of milsurp autoloaders, though the Garand saw the greatest use by far.

Speculation might suggest that contamination of the bore by bullet lube may have been adequate to protect the bore from any erosion, but it could also be logicly argued that the presence of organic material (lube) would have increased the carbon availability and exacerbated the erosion. I lean toward the former, having seen no evidence of erosion in any of my guns.

The effects of erosion increase dramitically with increases in pressure and volume of gases.
The .276 British for which the P-13 rifle was originally designed was found to burn out its bore in a fraction of the number of rounds fired compared to the .303 when both cartridges used Cordite propellant. A cartridge loaded to a lower pressure range and lower charge weight will not erode a bore nearly as fast as the same cartridge loaded to a maximum pressure range with a heavier charge of the same or similar propellant.
Also the effects of thermal erosion are often not easily detected by the naked eye.
Theres nothing at all unusual about a fairly low intensity cast bullet load not eroding a bore to any noticable extent, thats one of the major reasons for using cast boolit loads to begin with.

Bullet lubes are there to reduce friction which would other wise lead to leading and or mechanical erosion by means of abrasion.

The effects of cabon infiltration on long range match rifles which have had many thousands of maximum power high pressure loads fired through them aren't likely to show up on bores subjected to loads of far lower intensity. The deletrious effects of choking are also not so easily noticed when the ranges fired at are a mere fraction of those in which long range match rifles compete.
On the otherhand a great many of the rifles which are used with cast boolit loads are turn of the 19th century military rifles which have had many thousands of rounds of highly erosive ammunition fired through them and the effects are obvious to the owner. Cast boolit loads are often used in such rifles in order to extend the useful shooting life of these rifles which were on their last legs so far as full power mil spec ammunition went generation ago. Some might no longer be safe to fire with modern ammunition for that matter.
The 7mm Spanish rifles for example. Some saw very little use and retain very good to excellent bores, while others of the same vintage were hard used with highly erosive double base powders. I've seen the condition of some 7mm mausers described as a "hairy" bore due to turned up edges of gator cracking stripping away fibers from cleaning patches.
Other older rifles suffered microscopic pitting all over the surface of the bore due to corrosive primers. Tests run by the American Rifleman long ago indicated that bores with such surface pitting were actually more accurate when using cast bullets than a rifle of the same type with pristine bore. the microscopic pits held globules of bullet lube which under pressure acted as microscopic ball bearing greatly reducing friction and wear of the bullet surface. The same effect can be observed in the cross hatched honing of automobile cylinders, the honed surface holding lubricating oils longer than a polished smooth surface. Bosworth on the Rifle of the 1840's also describes this effect, his tests being run using brass rifled barrels with varying degrees of surface finish.

[Molly]

Hi Multigunner,

>Well Molly the reasons why conclusions on the mechanism by which the lubricated match bullets caused action failures of the Springfields aren't quite the same as those in which grease caused only a slight increase in velocity and noticable rise in pressure of the .303 are because the design philosophy and stage of development, plus the maximum chamber pressures of these cartridges and their platforms are far more different than you might think. Remember that the Lee Enfields were built to far looser tolerances and the chamber pressures were far lower. The throat of the Springfield was a tighter fit and bullets were a close match to bore size. The pressure curve of the propelants was also different.

You make some valid points, but (If I recall correctly) Hatcher's Notebook attributed it to grease incompressability preventing normal expansion of the neck and thus normal release of the bullet. When the practice was forbidden, the cracked and broken Springfields also went away. Me? "All I know is mostly from what I read." (Will Rogers, possibly paraphrased)

>As for Mann's conclusions, I found a PDF of his work and his reasoning is very straight forwards and easily understood. Perhaps you should read it again.

Perhaps I should. Refreshment is always a good thing. But my copy (along with nearly all my books) are packed away in storage, awaiting movement to a new home. But I don't think I mis-remember his conclusion that the throat pressure is high enough to expand bullet bases, and must invariably do so. If so, his explanation doesn't account for the fact that every single bullet he fired from that progressively shortened barrel had to be upset to fill the bore. But he got good accuracy from the long barrel, and horrible accuracy and upet from the shortened testing.

Seems to me that if the throat expansion is a constant, and results change, you need to look at what else changed. In this case, muzzle blast. I have other results that suggest rather strongly that muzzle blast is a primary failure mechanism of cast bullets. It is possible to take Lyman reloading data for a given bullet and maximum powder load, and calculate a relative muzzle pressure based on the ideal gas laws. It is then possible to back calculate a maximum powder charge for the same bullet used in a completely different round that develops the same relative muzzle pressure that is within half a grain from Lyman's data for the new round. I have made such comparisons between Lyman data for the 300 Win Mag and the 30-30 Win. The comparisons are compelling, but do not provide any clues regarding the actual mechanisms of failure. I can say that failure will occur at such and such a relative muzzle pressure, but I have no clue WHY the failure occurs.

But Mann, to the best of my recollection, did not consider muzzle blast among the factors he tested.

If so, then his results and mine are different, as are our conclucions. I find that WITH HARD CAST BULLETS, no evidence of base upset is observable on recovered bullets: The gas check shanks do not exhibit the bore-filling expansion of .22 bullets, the grease grooves are not shortened or expanded, etc.

>Now as for a bullet of .312 in a .308 bore, its likely that bumping up would have little benefit other than to insure that the bullet did not skid in the rifling allowing gas to leak past the corners of the portion of the surface in the grooves.

>Instances of skidding and its effects can be illustrated by the example of a .22 bullet known to have been fired from a certain rifle not being matched to the rifle by foresic examination. In that instance excessive grease in the bore coupled with the low pressure of the cartridge allowed the copper washed bullet to skid leaving the engraving of the lands far wider than normal, a lead bullet fired in the same barrel without grease filled out the grooves and prevented skidding.

We do disagree rather sharply here. I think I have seen and reproduced what you refer to as skidding, though I refer to it as engraving enlargement. In my tests, it began to occur when etching of the gas check shank had formed a complete or nearly complete encirclement of the gas check shank. The amount and type of lube was a constant. As the power of the load increased, bullets recovered with no or minimal etching also exhibited land engraving that was equal in width to the bore lands that produced them. However, as the power of the load increased, the width of the land engraving began to increase. Gas etching naturally began to be visible in the enlarged lands, first in the base band, and then progressing forward on the body of the bullet as the load was increased. This gas blowby etching was very obviously far worse or more extensive on the side of the land that did not force rotation of the bullet: IE, gas etching didn't occur on the side of the land that was pressed tightly against the body of the bullet. I also noted that when loads were too powerful for good accuracy, leading would flash at the muzzle from the trailing edges of lands, obviously from gas blowby from enlargement of the land engraving.

Beyond the pressure levels that produced this, shooting was wild, and I was not able to recover sample bullets for examination. However, a speculation that higher loads continued to produce greater land enlargement until it merged with the neighboring land to produce a smooth bullet of substantially bore diameter seems reasonable, which would account for the complete loss of accuracy.

>When the first Short Magazine Lee Enfields were produced they used the same MkVI cartridge as the earlier Lee Enfields, to maintain the same muzzle velocity from the 25 inch barrel of the SMLE MkI as from the LE rifle with its much longer barrel , the last fourteen inches of the bore was lapped in a reverse taper to relieve bullet friction.

This is the first I've heard of such a practice! While I don't question your account, I seriously question the logic of the armorers who would deliberately reduce the
velocity and energy of a round, and produce both reduced accuracy and barrel life. It seems that the most minimal testing of the concept would have weighed heavily and prohibitivly against it.

I notice that your examples often feature historical British military rounds, and in detail that would be beyond the experience of most shooters. By any chance are you in the British Military in some capacity that woule make you privy to such detailed histories?

>The effects of erosion increase dramitically with increases in pressure and volume of gases.
>The .276 British for which the P-13 rifle was originally designed was found to burn out its bore in a fraction of the number of rounds fired compared to the .303 when both cartridges used Cordite propellant. A cartridge loaded to a lower pressure range and lower charge weight will not erode a bore nearly as fast as the same cartridge loaded to a maximum pressure range with a heavier charge of the same or similar propellant.

No arguement here! I am of course aware that typical cast bullet loads exhibit lower pressures than factory rounds, and thus have much less propensity to cause throat erosion. But the consistent gas blowby that my recovered bullets exhibited from all but the lightest loads caused me to be alert for any problems. Evidence of gas blowby that I observed began as tiny spots of erosion or etching on the base of the bullet, just in front of the gas check, and located exactly at the land engraving on the gas check. I have never understood this, as it would seem that the engraving should produce the tightest fit, and certainly far tighter than the land engraving areas. Be that as it may, the etching grew progressively more extensive until the base of the bullet was encircled, and the land engraving began to enlarge along the sides of the bullet. With so much gas blowby evident in heavy loads, it seemed prudent to be alert for evidence of bore erosion, but I never found the slightest trace.

>Also the effects of thermal erosion are often not easily detected by the naked eye.
>Theres nothing at all unusual about a fairly low intensity cast bullet load not eroding a bore to any noticable extent, thats one of the major reasons for using cast boolit loads to begin with.

Granted, it may have been possible that erosion was present but invisible to my old eyes.

>Bullet lubes are there to reduce friction which would other wise lead to leading and or mechanical erosion by means of abrasion.

I have to disagree with you there too. As a youngster, I was fed all sorts of explanations for leading. The lead was abraded off of the bullet by bore irregularities, and was soldered to the surface by the propellent gases. Or it was removed by friction, or because the lube wasn't good enough, or (ad infinitum). I reasoned that these explanations, though superficially reasonable, could not possibly all be correct. I sat out to find out exactly what mechanisms produced leading. I compressed lead against clean steel in hydraulic presses. I checked for abrasive loss by pressing bullets through barrels to check for weight loss. I simulated the passage of the bullet against the bore by chucking bullets in high speed drills. I tested with and without lubes of various types, and at low and at high temperatures. And no matter what I did, I was unable to obtain the slightest adhesion of lead to steel unless the process was sufficiently intense to produce some melting of the lead bullet. And I compared my results with that of air rifles, where lead pellets can be shot for thousands of rounds at velocities over 1000 FPS without the slightest trace of leading.

MOLTEN LEAD IS AN ABSOLUTE REQUIREMENT OF LEADING. So I turned to considering sources of heat in the rifle, which reduced to propellent gas or friction. If friction were the culpret, it should be most evident toward the muzzle, where velocity is highest. Instead, leading is generally most severe at the beginning of the bore, where propellent gas is the only significant source of heat. I started using fillers beneath the bullet to form a sort of firewall. This was successful in markedly reducing the etching and leading, though it frequently reduced accuracy. But note that these varied results were obtained with all bullets lubricated with the same type and amount of lubricant. It was a constant, and could not have been able to cause or prevent leading.

I fianlly came to the conclusion that the source of leading was the same gas erosion that produced the etching of the bullet base described above, and that the primary role of lubricants was to proovide a surface contamination of the bore that retarded adhesion of the molten microscopic droplets etched from the bullet base. I also recognize that as the temperature of the gases increase with more powerful loads, the point will be reached when the surface tension of the lead that permits soldering will be reduced enough to enable it to adhere despite any lube contamination of the surface.

Lubes do play other roles, and sometimes improtant ones: Even light loads that produce no gas etching will exhibit different accuracy potential with different lubes. I am frankly ignorant of these roles, and of how lubes perform in them.

>Other older rifles suffered microscopic pitting all over the surface of the bore due to corrosive primers. Tests run by the American Rifleman long ago indicated that bores with such surface pitting were actually more accurate when using cast bullets than a rifle of the same type with pristine bore. the microscopic pits held globules of bullet lube which under pressure acted as microscopic ball bearing greatly reducing friction and wear of the bullet surface.

This sounds reasonable, but I have seen SO many 'reasonable' explanations turn out to be worthless that I have grown quite cynical in my old age. Are you aware of any effort to verify this? I question the logic of a soft bullet being prevented from being pressed into a microscopic pit filled with lube as being superior to a hard jacketed bullet that will not be pressed into the pit in any case.

[alamogunr]

I have been following this thread closely and I must compliment both Molly and Multigunner on a discussion in which there is both agreement and disagreement. BUT! There has been none of the rancor that often follows or accompanies disagreement. Both these gentlemen are to be commended. I sincerely hope others have noticed this.

John
W.TN

[StarMetal]

Molly,

I don't tag along with your leading theory. Leading can and does occur due to high stresses of the bullet sliding against the bore because of lack of lubricant and in some instances a rough bore. Explain why, with jacketed bullets, there are jacket deposits along the whole length of the bore. I'd say the reason leading is more evident near the breech end is because that's were the bore is the most rough due to erosion inaddition to high temperatures because of the powder burning which add to the stresses of the bullet sliding along...in other words making it easier for the lead alloy to gall off onto the bore. Try shooting a non lubricated cast bullet void of any oils or dry lubes and tell us what happens. I also believe that air rifle pellets are lubed. Be nice if you could use compressed air to drive a 30 caliber non lubed bullet out of a rifle barrel at gun powder velocities and not get any leading. That would be an eye opener in the leading question. Next you'll be telling us that chalk marks the slate on the blackboard because it's melting.