Do they "bump up" or not???

[Knarley]

Now this is going to sound like a goofy question, maybe..........
I read some where else, that a cast boolit does not bump up if you are using smokeless powder.
I had mentioned using 20-1 alloy. And was told that it wouldn't bump up, and am really at a loss for why.
Now I understand that harder alloys would be different, and I'm not arguing that.
Confused as usual,
Knarley

[DougGuy]

What caliber, what gun, what boolit style and weight?

I have always been under the impression that the softer an alloy is, the lower the pressure required to get it to obturate or "bump" up.

[GhostHawk]

I'm with DougGuy, specifics can make a big difference.

I always suspected powder choice can be a factor as well.
A slower powder should not push it as hard as a faster one.

[RPRNY]

Any smokeless powder suitable for cast bullets will produce obturation in a 20:1 alloy that is at least a tight fit into the lands. If it is undersized, perhaps not.

[Hannibal]

Never mind. I defer to those more experienced than I.

[Digital Dan]

Now this is going to sound like a goofy question, maybe..........
I read some where else, that a cast boolit does not bump up if you are using smokeless powder.
I had mentioned using 20-1 alloy. And was told that it wouldn't bump up, and am really at a loss for why.
Now I understand that harder alloys would be different, and I'm not arguing that.
Confused as usual,
Knarley

From the LASC web page:


Bullet BHN / "Minimum" Chamber Pressure For Lead Alloys (PSI)

The formula (from the pages of HandLoader Magazine) to determine at what pressure an alloy of given BHN will obturate the base of the bullet and seal the bore. If the bullet is too hard to obturate, gas cutting usually occurs on the base band on the non-driving side of the rifling and barrel leading is likely. Simply multiply the alloy BHN by 1,422.


Example: Alloy BHN of 12 multiplied by 1422 = 17,064. An alloy of 12 BHN should be used with a load that develops a "minimum" of 17,000 psi. Need more info on minimum / maximum alloy BHN? These Glen E. Fryxell articles explain alloy BHN in easy to understand language.

http://www.lasc.us/CastBulletNotes.htm




SAECO Lead Hardness Tester Conversion To BHN


Certified Alloys
SAECO
Brinell


Pure Lead
0 - 1
6


20 - 1
6 - 7
10


Hardball
8 - 9
16


Linotype
9 - 10
18 - 20

[geargnasher]

Yep, they sure can, but not always.

Gear

[kentuckyshooter]

From what reserch i have done and as i understand it cart boolits can and do obtrue. This was a mater of great significance to produce acracy with early muzzel loading rifles shoting a mini. Look at the base of any mini cast of pure lead for use with these early rifles and u will observe a hollow cavity that forms a skirt. This would expand out opon fireing to seal the gas in the bore. Newer firearms using smokeless powder still obtrue but as an accepted rule of thumb u should not religh on it. Super hard allows shot from rifles will show very little bump up even though they are being push very hard.
If you follow the moto fit is king then boolit bum up ir rendered a mute point as at .001 to .002 over sized boolits will be swaged down by the barel instead of bumped up by the powder charge and provide a more uniform seal from round to round.
Just my 2 cents im sure some one a lot more knowlageable than me will be able to give more details or point out things i have overlooked.

[geargnasher]

So, why don't you clear it up for us then?

Gear

[RPRNY]

In post #6, Digital Dan provided the actual formula for obturation by BHN.

A 1:20 alloy is about BHN 10. Ergo, any smokeless powder and bullet weight combination generating chamber pressure of 15,000 psi + will obturate the bullet, provided it is at least slightly oversize to the bore.

Under bore size and you may get gas cutting or pressures below advertised, possibly low enough not to obturate.

[Digital Dan]

I would suggest that much dialog that I've read here @ Cast Boolits goes to cast bullets and very mild loads for plinking or special applications and little if any consideration is given to alloy or pressure. My experience, for whatever it might be worth, if you put a load together with consideration of alloy and pressure likely to be generated by the charge, smokeless powder will indeed promote obturation. In point of fact, heavy smokeless loads will promote that occurrence with jacketed bullets in many cases, particularly when those bullets are amenable. An example that comes to mind is typical hunting loads using the Nosler Partition.

While I do fiddle with mild loads for certain applications, most of my field loads using cast bullets are not mild by any stretch of the imagination. They do obturate. The phenomenon isn't magic. Put enough pressure on any metal and it will deform, else bullet makers would not be able to swage bullets.

[44man]

I agree, enough pressure and jacketed also "bump up".
Going too soft and boolits can slump all out of shape.
I have never found a reason to bump up, fit is first and a strong enough alloy so a boolit does not slump. I never got too soft to shoot.
I have years of experience with pure Minie' balls in muskets too and BP is easier on a boolit then smokeless yet to even hit paper the Minie' had to fit first or they slump off center. By lapping molds I went from missing a 4'x4' board at 50 to hitting steel at 200 meters. I have never believed in using powder to make a boolit fit.

[JonB_in_Glencoe]

Do they "bump up" or not???
Most likely, they do with 20:1
as others have asked, if you were to give us some more details, we could probably give a more definitive answer.
Jon

[Digital Dan]

fit is first

That's the Holy Grail right there. Hoping a gas cut bullet will obturate is sorta like closing the barn door after the horses have left.

It is a mistake to compartmentalize any single facet of casting or hand loading in search of success. One must look at the broad stage and embrace that instead.

[44man]

Absolutely, to depend on BHN alone has nothing to do with what pressures do.
Low velocity loads can damage a boolit faster then a heavy load too. You think "only 17,000" but you insert it instantly at the base. Then you forget slump and skid. Neither of those make "FIT." Once the worm is out of the ground, any bird will get it. Once you gas cut don't expect a boolit to seal in the rifling, those gas molecules are VIOLENT.
I know what leading is from trying wrong things, Now I never need a patch down a bore-EVER.
The day I shoot 20 to 1 is also NEVER! OOPS, forgot BPCR.

[Knarley]

O.K.
So the answer is yes, they will, under certain conditions. I'm cool with that.
To those who need to know; the conversation was that of a 38-55 load going from BP to Smokeless that were close in comparison.
But after doing more digging around, and further conversation, the answer is yes but not always.
The fact that Black Powder explodes.........and Smokeless "burns real fast" this most likely the main reason. When some thing explodes, you get an immediate "SQUISH" factor. When some thing burns real fast, not so much, unless it burns really, really fast, then some squish factor may raise it's head.
The hard ness of the boolit would come into play, but in this scenario it is not part of the equasion, nor is the weight of the boolit, for it is not a factor either.(Exact same boolit)
Thanks for all of your answers, they have helped shed light,
Regards,
Knarley

[44man]

O.K.
So the answer is yes, they will, under certain conditions. I'm cool with that.
To those who need to know; the conversation was that of a 38-55 load going from BP to Smokeless that were close in comparison.
But after doing more digging around, and further conversation, the answer is yes but not always.
The fact that Black Powder explodes.........and Smokeless "burns real fast" this most likely the main reason. When some thing explodes, you get an immediate "SQUISH" factor. When some thing burns real fast, not so much, unless it burns really, really fast, then some squish factor may raise it's head.
The hard ness of the boolit would come into play, but in this scenario it is not part of the equasion, nor is the weight of the boolit, for it is not a factor either.(Exact same boolit)
Thanks for all of your answers, they have helped shed light,
Regards,
Knarley
NO, NO, NO, BP does NOT explode in a gun. It will be a progressive burn and if the barrel is too short you will have more unburned powder exit the muzzle then you get with smokeless. It starts with a low pressure and builds over a longer period. You will never duplicate it with smokeless.
There are all kinds of BP from flash to explosives with fire works in there somewhere but GUN powder does not explode. It BURNS increasing gas.

[vzerone]

Not to hijack the thread, but here is an interesting read on how fast does BP burn.

http://www.ctmuzzleloaders.com/ctml_experiments/bp_burning/bp_burning.html


(http://www.ctmuzzleloaders.com/ctml_experiments/bp_burning/bp_burning.html)

[montana_charlie]

NO, NO, NO, BP does NOT explode in a gun. It starts with a low pressure and builds over a longer period. You will never duplicate it with smokeless.
A 'soft' bullet fit snugly in the mouth of a brass case will 'bump up' enough to obturate before it even moves forward, if the pressure is sufficiently high.

The fact that a pressure peak of X psi is recorded when a cartridge is fired, doesn't mean that a bullet would be bumped up early enough to prevent bypass.

If, as said above, 20-1 alloy needs 15,000 psi to 'bump', that pressure needs to be reached immediately ... not after the bullet is a quarter of the way down the bore.
Black powder provides that early pressure peak whereas (more progressive) smokeless will not.


Actual pressure curves say you are almost perfectly backward in your description.


http://img.photobucket.com/albums/v497/3855Win/45_70_pressures.jpg

http://img.photobucket.com/albums/v497/3855Win/45_70_pressure3.jpg

[geargnasher]

Thank you, Charlie, most excellent description and pressure traces.

You said something else important that has been missed entirely "...'bump up' enough to obturate...", which is technically correct for this discussion. The way I use the verb "obturate", it does NOT mean "bump", "slump", "deform", or any action occurring to the bullet itself, it means "to obstruct a tube", or "seal the" and refers to the action of the bullet sealing the bore.

Dictionary dot com isn't THE authority on everything, but this is what they say about it:

verb (used with object), obturated, obturating.1.to stop up; close.

2.Ordnance. to close (a hole or cavity) so as to prevent a flow of gasthrough it, especially the escape of explosive gas from a gun tube during firing.


Gear

[44man]

Not to hijack the thread, but here is an interesting read on how fast does BP burn.

http://www.ctmuzzleloaders.com/ctml_experiments/bp_burning/bp_burning.html


(http://www.ctmuzzleloaders.com/ctml_experiments/bp_burning/bp_burning.html)
I see where he says a true progressive after all. Of course powder granule size matters. you do not shoot FFFFG from a rifle but choose the best. FFG for most. Slower or faster from some. But it is a progressive burn needed. Does anyone shoot FFFFG from a rifle? Yet you want Bullseye.
BP has bulk to push a boolit before gas can reach it. More a wad then unique has gas.

[vzerone]

Here's an extensive U.S. Army report on BP burn.

http://www.dtic.mil/dtic/tr/fulltext/u2/a129087.pdf

[Knarley]

For me, "Bump up" is easier to spell than "obturate". My computer puts a red line under it no matter how I spell it. This IS the correct way...........I looked it up.
A lot of people use the terms interchangeably, I know I do.
As far as BP not exploding in the gun, I know it doesn't explode the gun, but when an explosive goes off................
Smokeless is NOT an explosive, so when it goes off, it burns really, really fast..............
I just could not believe that a boolit would not obturate, swell up, bump up or get fatter after the trigger was pulled is all.
Hey Charlie, your chart is way cool!!

Knarley

[44man]

Thank you, Charlie, most excellent description and pressure traces.

You said something else important that has been missed entirely "...'bump up' enough to obturate...", which is technically correct for this discussion. The way I use the verb "obturate", it does NOT mean "bump", "slump", "deform", or any action occurring to the bullet itself, it means "to obstruct a tube", or "seal the" and refers to the action of the bullet sealing the bore.

Dictionary dot com isn't THE authority on everything, but this is what they say about it:

verb (used with object), obturated, obturating.1.to stop up; close.

2.Ordnance. to close (a hole or cavity) so as to prevent a flow of gasthrough it, especially the escape of explosive gas from a gun tube during firing.


Gear







Super. My definition entirely. It means SEAL, not to destroy a boolit in the process. Silly putty down the bore seems to be what most want.
Expand to seal the throats with slump that ruins the boolit, wipes grease grooves away, blows lead and lube out the gap. and will obturate somewhere down the bore to get a seal is like having a light saber where light stops at 3'. Aliens can transport through solid walls and take you through solids and can control light but we are not there. Making cast shoot is like making sense of how 40 ton blocks were placed before the stone age. Yeah, cut with copper chisels.

[Markbo]

... The day I shoot 20 to 1 is also NEVER! OOPS, forgot BPCR.....

Just curious...what do you shoot in say cowboy loads up to full velocity magnum handguns?

[vzerone]

I think we're getting a little off track. Many of us fit the throat or fit the cylinder throat in a revolver. That would make the bullet always "fatter" then the bore groove. So in that sense it's going to seal the bore/groove without obturation, but it's nice to have that obturation for an insurance policy. It's a different situation in the case of a BP Minie ball. It needs obturation to seal. In the case of the TC Maxi-Ball the band at the nose seals the bore/groove after seating because it gets engraved. The rest of the body then "bumps" up for a total seal and I might add much better accuracy.

One mentioned many of us want to shoot putty down our barrels. Not so for me. If that happens you have exceeded the pressure limits of the alloy.

I like my bullet to bump up, but I also want that bump to stop at a particular place on the bullet.

[Harry O]

All bullets bump up to some extent. When pressure is applied, all metal yields some (check the definition of modulus of elasticity -- all metals have it). The question is, does it bump up the correct amount? It it does not bump enough or if it bumps up too much, it is inaccurate.

There is a point called the yield point (or yield pressure or yield strength) for metals, including lead, lead/tin, and lead/tin/antimony mixtures. With powder pressure between zero psi and the yield point, the bullet will return to its original size and shape as soon as it leaves the barrel. If, the expansion of the bullet also seals off any minor gaps between the bore or rifling and the bullet, you have an accurate load. Both are good, but sometimes hard to achieve.

If it goes over the yield point it is less accurate, it will not return to its original shape -- including a necessary flat-base. If it does not seal off the bore, it is less accurate. Anyway, there are a lot of things that enter into what you are asking and so far, I am not aware of a complete and easy to calculate all of them. In general terms, faster powders will bump up more. Slower powders less. Harder bullets will bump up less. Softer ones more. However, ALL of them bump up.

[RPRNY]

Any smokeless powder that is suited to cast bullets, especially of the softer alloys, will obturate a 20:1 alloy bullet that is reasonably sized.

[montana_charlie]

Thank you, Charlie, most excellent description and pressure traces.

You said something else important that has been missed entirely [COLOR=#333333]"...'bump up' enough to obturate...", which is technically correct for this discussion. The way I use the verb "obturate", it does NOT mean "bump", "slump", "deform", or any action occurring to the bullet itself, it means "to obstruct a tube", or "seal the" and refers to the action of the bullet sealing the bore.
Well, Gear, it's obvious that 44man didn't get the message on the difference between black and smokeless powders ... and you can see from the later posts that using big words (like obturate) just confuses many bullet casters, even though you posted the actual definition for them.

[Digital Dan]

Not wanting to muddy the water, but the discussion about whether BP is an explosive or propellant has little merit here. Good images of the pressure curves earlier get right to the point. Whether something is or is not an explosive is irrelevant to this discussion. Even C4 has a burn rate....it is other characteristics which define what is and isn't an explosive.

[vzerone]

Not wanting to muddy the water, but the discussion about whether BP is an explosive or propellant has little merit here. Good images of the pressure curves earlier get right to the point. Whether something is or is not an explosive is irrelevant to this discussion. Even C4 has a burn rate....it is other characteristics which define what is and isn't an explosive.

Load one of your cartridges with C4 then tell me about it having a burn rate. BP burns....simple as that. It's just fast and some smokeless powder are as fast. Look how the Trailboss compared on the pressure chart. I will agree that BP is a very low grade low explosive. Most true explosives detonate whether in the open or confined. BP seems more an explosive when confined. Look at natural gas. When it's confined in a house such as when there is a gas leak and their is a spark to set it off it's very impressive! But is it classified as an explosive?

[stubbicatt]

I may be off base here, but I have found that even PB bullets cast of "soft" alloys like 20-1, which I prefer for most uses, shoot well in different firearms up to somewhere near 1,700 fps., if they are of the proper diameter, and carry enough, soft lube. I have tried bullets cast under groove diameter, and so far, even with black powder, they don't perform all that well, and leave leading in the throat area.

[Toymaker]

Knarley, an interesting and very complicated question. AND for the same caliber I'm researching. I read the same thing in "The Paper Jacket" and have been playing with the physics ever since. IF you keep everything the same except the powder, and the powder charge results in the same velocity, both bullets are going to "bump up" (nearly equally). In both cases all the forces trying to keep the bullet from moving are equal. The structural resistance of the bullets are the same. The forces trying to move the bullet, over the critical time period, are nearly the same.

For me the main difference is the fact that I use bullets with a greater structural resistance with smokeless powders. In "people speak", my smokeless bullets are harder. So I get less "bump up". Other folks I've talked with also use harder bullets with smokeless.

I gave the issue to a rocket scientist friend (NASA engineer/physicist) and he thought about it for a week. When we sat down and he started to explain it all my eyes glazed over. He looked at me and said "Your source information is mistaken. Slump is equal."

So ,,,,, I'm not going to worry about it anymore.

[44man]

Just curious...what do you shoot in say cowboy loads up to full velocity magnum handguns?
I use WD WW metal for full power loads and can shoot 50-50 if I oven harden to 18-20 BHN. However they are too explosive on deer.
I did a lot of experiments with lighter loads of Unique and 231 by changing the alloy little by little and seeing groups. I found that when I got to 28 and 30 BHN, groups tightened to the point I shot better 50 yard groups then softer lead shot at 25 yards. I used the 44-245-SWC for these.
Hard lead actually out shot WD WW metal by a wide margin.
My conclusions are two, fast powders damage a boolit more and the harder shoulders can clock the cylinder better.
You can see the first targets, left at 25 and right is 50, 22 BHN. Then the second set, left 25 and right 50, 30 BHN. 158578158579 You can plainly see results but I did not take pictures of softer lead tests, camera was dead. But they were no where near these. Some at 3" at 25 and leading in the bore.
The patch from the bore with 30 BHN shows no leading at all.
By the way these boolits are .430", shot from a .430" groove and .4324" throats. Less bump up from 30 BHN shows me hard lead does not cause leading.
My 330 gr with 21 gr of 296 shot a 1-5/16" group at 200 yards and it is also .430" but my RD 265 is .432" and will hold 3/4" at 50 and 1-1/4" at 100 with 22 gr of 296. But I see no real difference fitting to groove or throats. I get no leading and have not cleaned the bore in three years. This SBH has near 81,000 heavy loads through it.
I have been shooting the .44 since 1956 and serious testing started in 1980 when I started IHMSA and it has never ended.

[44man]

Now BP is something I have been shooting forever, about 65 years I figure. It burns fast but never develops the pressure or the instant pressure of smokeless. It also works better in longer barrels.
I seen a test done long ago with FFFG where a hunk of water pipe was filled full and end caps screwed on. they had a fuse hole in one end, inserted a fuse, lit it and went behind a barricade. The pipe did not explode, all the gas went out the fuse hole.
Then my friend compressed loads in small batches in a 45-70 until he had a huge load, velocity dropped a huge amount and plugs of powder blew out the muzzle to burn in the grass. Much fun to see.

[Ballistics in Scotland]

Load one of your cartridges with C4 then tell me about it having a burn rate. BP burns....simple as that. It's just fast and some smokeless powder are as fast. Look how the Trailboss compared on the pressure chart. I will agree that BP is a very low grade low explosive. Most true explosives detonate whether in the open or confined. BP seems more an explosive when confined. Look at natural gas. When it's confined in a house such as when there is a gas leak and their is a spark to set it off it's very impressive! But is it classified as an explosive?

What could in theory be called an explosive is a mixture of natural gas and air, which is something you can't buy in a cylinder. Pure natural gas emitted in the simplest way will burn with a rather unsatisfactory smoky yellow flame. Even a gas appliance is arranged to provide a better air supply than that, and most of all in blowtorches with their air entry ports.

Similarly black powder is classified in most countries as an explosive because of what can happen (an outburst of hot gas fast enough to blow a building apart if there is enough of it) when it is ignited unconfined and at atmospheric pressure. Smokeless powder thus ignited can ignite the building and very severely burn people. But it won't explode unless the quality of the building are enough to constitute confinement.

Black powder is a low explosive, because it obeys Piobert's Law, i.e. even in confinement it burns, from the outside in, like the skins of an onion being removed in succession. With high explosives something very different happens. A wave-front passing through the grain or chunk triggers the solid-to-gas reaction, and that wave-front is an impact commonly travelling at 7000 or more metres per second. The classic example was a slab of blasting explosive unconfined on a steel plate, into which it printed the government mark imprinted on the slab. C4 can be detonated in this way by a percussive shock-wave from a detonator, and also has the much slower burning rate, not very different from pre-safety nitrate film stock, by which soldiers light it with a match to boil water.

Confinement increases the burning rate of powder. With black powder the speed with which the surface of a burning grain shrinks (and thus gas is produced) is approximately proportional to the pressure upon it. With smokeless, it is a lot more than proportional. In simple terms it means that anything that would run up pressure a little with black powder, runs it up a lo with smokeless. It is also why black powder hand firearms usually benefit from a longer barrel than smokeless ones, although black powder artillery can't benefit from the length of barrel that smokeless artillery does.

[Ballistics in Scotland]

From the LASC web page:


Bullet BHN / "Minimum" Chamber Pressure For Lead Alloys (PSI)


The formula (from the pages of HandLoader Magazine) to determine at what pressure an alloy of given BHN will obturate the base of the bullet and seal the bore. If the bullet is too hard to obturate, gas cutting usually occurs on the base band on the non-driving side of the rifling and barrel leading is likely. Simply multiply the alloy BHN by 1,422.




Example: Alloy BHN of 12 multiplied by 1422 = 17,064. An alloy of 12 BHN should be used with a load that develops a "minimum" of 17,000 psi. Need more info on minimum / maximum alloy BHN? These Glen E. Fryxell articles explain alloy BHN in easy to understand language.

http://www.lasc.us/CastBulletNotes.htm





SAECO Lead Hardness Tester Conversion To BHN



Certified Alloys

SAECO

Brinell



Pure Lead

0 - 1

6



20 - 1

6 - 7

10



Hardball

8 - 9

16



Linotype

9 - 10

18 - 20









In most respects this table is pretty good. But there are two disturbing influences. One is that if gas pressure leaks into the grooves, it will impede bumping up of the bullet, and perhaps even squeeze or erode it smaller.

Another, which I think nobody has mentioned, is the inertia of the bullet. If you could find a substance as malleable as lead but as light as a feather, pressure on the base would have almost no tendency to expand it, and would simply accelerate the bullet. If it is undersize, undersize is what you get. A heavy metal would expand more.

Bullet alloys don't vary very much in density, and so the greater the length of the bullet, the greater its tendency to expand. In particular a long unsupported nose is the kind of bullet in which accuracy is likely to suffer most, and a full wadcutter the least. If a tapered nose is widening and shortening, it may do so asymmetrically.

[44man]

BP IS an explosive and it is conditions that vary that where it either blows up or burns. It does not explode in a gun unless you did something stupid like a boolit or ball way off the powder.
As you lengthen a barrel with it you will see velocity increase the same as a slow smokeless in a magnum. It is still burning as it pushes.
Load too much for the gun and velocity will decrease from pushing more weight. That is powder not burning yet.
Sorry if BP exploded in a gun you would be eating steel.

[44man]

BP is not a pure explosive like Dynamite where nitroglycerin is soaked in various components like clay, sawdust, etc.
You do not want an explosive in a gun.

[Knarley]

Nitroglycerin IS used in gun powder, sorry.

[44man]

Nitroglycerin IS used in gun powder, sorry.
True but not as an explosive.

Currently, propellants using nitrocellulose (detonation velocity (https://en.wikipedia.org/wiki/Explosive_velocity) 7,300 m/s (23,950 ft/s)) (typically an ether-alcohol colloid of nitrocellulose) as the sole explosive propellant ingredient are described as single-base powder.[18] (https://en.wikipedia.org/wiki/Smokeless_powder#cite_note-Chemistry297-18)
Propellants mixtures containing nitrocellulose and nitroglycerin (https://en.wikipedia.org/wiki/Nitroglycerin) (detonation velocity (https://en.wikipedia.org/wiki/Table_of_explosive_detonation_velocities) 7,700 m/s (25,260 ft/s)) as explosive propellant ingredients are known as double-base powder.[19] (https://en.wikipedia.org/wiki/Smokeless_powder#cite_note-Chemistry298-19)
During the 1930s triple-base propellant containing nitrocellulose, nitroglycerin, and a substantial quantity of nitroguanidine (https://en.wikipedia.org/wiki/Nitroguanidine) (detonation velocity 8,200 m/s (26,900 ft/s)) as explosive propellant ingredients was developed. These propellant mixtures have reduced flash and flame temperature without sacrificing chamber pressure compared to single and double base propellants, albeit at the cost of more smoke.
In practice, triple base propellants are reserved mainly for large caliber ammunition such as used in (naval) artillery (https://en.wikipedia.org/wiki/Artillery#Propellant) and tank guns (https://en.wikipedia.org/wiki/Tank_gun). During World War II it had some use by British artillery. After that war it became the standard propellant in all British large caliber ammunition designs except small-arms. Most western nations, except the United States, followed a similar path.
In the late 20th century new propellant formulations started to appear. These are based on nitroguanidine and high explosives of the RDX (https://en.wikipedia.org/wiki/RDX) (detonation velocity 8,750 m/s (28,710 ft/s)) type.

[Markbo]

I use WD WW metal for full power loads and can shoot 50-50 if I oven harden to 18-20 BHN. However they are too explosive on deer.
I did a lot of experiments with lighter loads of Unique and 231 by changing the alloy little by little and seeing groups. I found that when I got to 28 and 30 BHN, groups tightened to the point I shot better 50 yard groups then softer lead shot at 25 yards. I used the 44-245-SWC for these.
Hard lead actually out shot WD WW metal by a wide margin.
My conclusions are two, fast powders damage a boolit more and the harder shoulders can clock the cylinder better.
You can see the first targets, left at 25 and right is 50, 22 BHN. Then the second set, left 25 and right 50, 30 BHN. 158578158579 You can plainly see results but I did not take pictures of softer lead tests, camera was dead. But they were no where near these. Some at 3" at 25 and leading in the bore.
The patch from the bore with 30 BHN shows no leading at all.
By the way these boolits are .430", shot from a .430" groove and .4324" throats. Less bump up from 30 BHN shows me hard lead does not cause leading.
My 330 gr with 21 gr of 296 shot a 1-5/16" group at 200 yards and it is also .430" but my RD 265 is .432" and will hold 3/4" at 50 and 1-1/4" at 100 with 22 gr of 296. But I see no real difference fitting to groove or throats. I get no leading and have not cleaned the bore in three years. This SBH has near 81,000 heavy loads through it.
I have been shooting the .44 since 1956 and serious testing started in 1980 when I started IHMSA and it has never ended.

That is extremely interesting. That just flies in the face of all the "softer is better" advice. Do you find these same results with PC and non PC loads?

[DougGuy]

I don't buy into the "sometimes but not always" school of thought as bible.. In all reality, the phrase is true, in that if you keep all the variables in a load the same and only change for progressively harder alloy, yes you will reach a point where pressure and the inertia of pulling crimp are not enough to "bump" up the boolit because the alloy is harder and therefore integrally stronger than the forces applied against it.

Truth is, a boolit is a static object, and when struck from behind with a pressure wave that will exert enough force against the boolit to cause it to pull crimp and begin to travel toward the muzzle, ALL boolits will "bump up" if the force applied to it is greater than it's integral strength, AND there is room along the sides of the boolit for expansion.

If there isn't any room along the sides, and the pressure wave generated from firing is indeed stronger than the alloy of the boolit, it will shove the back of the boolit forward causing the lube grooves to collapse and as 44man calls it "slump" until they are pushed out far enough until the bore walls are met and there is no more available space for the alloy to be pushed into.

Under normal firing conditions, a typical alloy for a handgun might be 20:1, 50/50+2%, Lyman #2, COWW, all of these are pretty much BHN15 or softer, and with charges of powder you may find in the original standard pressure .45 Colt load, .44 Special load, .45 ACP load boolits may not bump up very much if any at all. Once you get this same alloy and calibers to say +P pressures, obturation is more or less guaranteed. Boolits will leave the cylinder sized to the cylinder throats from being bumped up when fired. At magnum pressures or Ruger Only pressures, even a harder BHN22 alloy will bump up, where +P pressures would not be enough to bump up a boolit cast in BHN22 alloy. Yes they will become engraved by the rifling, but this does not mean they "bumped up" before entering the bore.

The above paragraphs are what I use as a guide, I really don't need the formulas even though they are much more accurate than my simple guesstimaged figures. If you can scratch it with a fingernail, it will bump up with standard pressures regardless of what powder or primer is used, UNLESS it is just a featherweight boolit which is too light to succumb to the forces shoving it out of the case and into the bore.

[scottfire1957]

Now this is going to sound like a goofy question, maybe..........
I read some where else, that a cast boolit does not bump up if you are using smokeless powder.
I had mentioned using 20-1 alloy. And was told that it wouldn't bump up, and am really at a loss for why.
Now I understand that harder alloys would be different, and I'm not arguing that.
Confused as usual,
Knarley



I'm thinking the "simple" answer is, yes, they will "bump up," IF the pressure applied to the base of the bullet is applied in the proper time and amount. Doesn't matter the propellant.

I'll let you figure out the proper time and amount.:D

[vzerone]

actually I would prefer to leave that up to you, after that remark talk about a snide remark. And yes C4 does have a burn rate that is fast enough it is defined as detonation velocity.

44 Man mentions RDX well heck gents that is what is mixed with a plasticizer (which is inert) to make C4.

Detonation is not a burn rate. Maybe this will help you understand that. In the study of weapons, a low explosive burns, but a high explosive (such as C4 sgt.mike) detonates-a very different phenomenon (read that sgt.mike a phenomenon...not a burn rate what so ever). An initial shock compresses a high-explosive material, heating it and causing chemical decomposition. The formation of chemical products releases enormous amounts of energy in just billionths of a second. I guess we can take that as sgt.mikes burn rate for C4. This process sustains the shock wave, which travels at supersonic velocity. All this happens almost instantaneously to produce a blast of hot rapidly expanding gases.







I don't think what I told the poster was a snide remark, it was to point out that explosives can't be used for cartridge powder.

[303Guy]

I have fired test loads into a catch medium. One such was using a particular alloy and a paper patched boolit that had been sized in die with two diameters and a transition taper between. The idea was to fit the throat, only in this gun the fit wasn't perfect so the transition taper didn't fully fit the throat geometry. Well, the rifling engagement showed up this transition zone. I then softened the alloy a bit and loaded up and identical load and this time the transition zone showed a definite bump up. That was using a light load of some smokeless powder, light enough that the boolit could be captured virtually intact.

Then I've had other boolits that have showed nose slump! Short nose too.

[Lloyd Smale]

to answer the original question. Yes they do unfortunately when your using lead to soft for the pressures your loading too.. Some consider this a good thing but if a GOOD gun its never a good thing to have your bullets deform. Ive seen **** guns shoot soft (bumped up) bullets better but its really rare that you will find a good gun that does better with soft bullets or leads because you used to hard of a bullet. Ill put it this way. If you had a tack driving match 308 heavy barreled rifle and went and bought some high dollar match bullets would you want your gun to deform them into a blob of copper and lead. Would you expect the best accuracy that gun could deliver with a bullet that did that. I would suspect that the reputation full wadcutters got in the past was due to the fact that gun tolerances were loose at best then and a wad cutter started as a blob of lead and didn't change shapes as much as other bullets.

[44man]

I firmly believe all boolits will bump and even the 30 BHN I shot will also. The key is to recover boolits that are the same as you cast. Nose set back should not be found.
I don't think a bore ride should expand to fill the grooves. Lee makes a .45 mold and boolit that was shown to slump off center by BPCR shooters. I have the mold and never got it to work either.
I use pure only in a ML and 20 to 1 and even 30 to 1 in BPC. This is where boolit design that will hold shape is best. Yes, they bump to fit but it is still better to fit first. The Maxi ball works that way. If fit is there, the boolit will be confined by the bore straight.
A revolver brings in more with the throats, gap and forcing cone impact. This is where I believe ogive shape is important so you do not want a boolit to slump before the cone is reached. You need the ogive to steer and pull the cylinder to alignment as no holes are perfect. The extreme wear I have found in a revolver was due to it being too tight. I would never believe a cone and half the rifling could be worn away on one side. Jacketed bullets even wore the throats oblong from the side force.
The very worst guns I found for leading were .38 revolvers shooting dead soft wad cutters. I posted before about my job of cleaning .38's from the Cleveland police I shot with. Cylinder fronts and frames were coated in lead from the gap. I could clean the bores easy but to get lead off the outside without harming the blue was something I never want to do again.
Take pressures up to a .357 and larger with those boolits and you could kill deer at the side of the gun. You can't believe how much lead comes out of that space.
I agree with DougGuy about throats and all else he says. Lloyd knows too.
I can say with truth that I never seen too hard lead a gun if you have a seal to gas.
I do not believe if your throats are oversize that you must fit to them or bump to fit them. There is some allowance there as long as the boolit seals the grooves. A straight start is much more important.

[Digital Dan]

Load one of your cartridges with C4 then tell me about it having a burn rate. BP burns....simple as that. It's just fast and some smokeless powder are as fast. Look how the Trailboss compared on the pressure chart. I will agree that BP is a very low grade low explosive. Most true explosives detonate whether in the open or confined. BP seems more an explosive when confined. Look at natural gas. When it's confined in a house such as when there is a gas leak and their is a spark to set it off it's very impressive! But is it classified as an explosive?

C4 in rifle charges has been done, likewise with TNT. Unconfined gas? You mean like fuel vapor bombs?

If you care to discus this further start another thread. Sorry I brought it up here.

[vzerone]

C4 in rifle charges has been done, likewise with TNT. Unconfined gas? You mean like fuel vapor bombs?

If you care to discus this further start another thread. Sorry I brought it up here.

Well let's make it fit with this statement. Wow! that sure would bump a bullet up!

Sorry I got off track, but it sort of was brought up if BP actually had a burn rate or is more a low grade explosive.

I agree with Lloyd that the less damage done to the bullet the better, after all it's getting sliced by the rifling grooves.

[Markbo]

So 44man, Lloyd & Doug... say for .41 mag from plinking to hit GCed hunting loads will one alloy work, i.e. COWW + 1-2% tin or will I have to make multiple alloys?

[vzerone]

So 44man, Lloyd & Doug... say for .41 mag from plinking to hit GCed hunting loads will one alloy work, i.e. COWW + 1-2% tin or will I have to make multiple alloys?

You don't need the extra tin, you don't need the extra tin. You also don't need the extravagant alloys for just plinking. Why use your more expensive and harder to get alloys up for that? I like multiple alloys.

[DougGuy]

The gas check allows you to shoot softer alloy without leading and without damage to the base of the boolit so for that reason no you should not have to use separate alloys. Plinking with a plain base boolit and then loading full house magnum loads with a plain base boolit yeah you might need a harder alloy for the magnum load but it's a whole different story with a gas check. Softer alloy and soft lube are the order of the day for my GC boolits in my .44 and .45s. 44man does his gig differently and he casts hard. Both work.

I personally favor 50/50+2% and Felix lube with the Lee RF boolits in both calibers, both gas checked. It's soft enough to scratch with a thumbnail. I have very good accuracy, VERY good consistency and never have to clean the barrels. All that remains in the bores are powder and lube residue, no leading, and a lube star at the muzzle. These are my hunting loads for deer and for hogs and bear I would load a slightly harder alloy like Lyman #2 in the same exact boolit not to prevent leading but to keep the boolit from expanding so it will penetrate more.

[vzerone]

I feel gas checks in revolvers is for when you're pushing the envelope. If you use a softer alloy you shouldn't be using a hot load. That's exactly what happen when S&W came out with the 44 mag and loaded with those semi wadcutter lead bullets. Leaded like the dickens and those bullets were really soft.

The more excess tin you put in your alloy the more chance it's going to lead up your barrel.

[Lead pot]

This subject on how much a bullet obturate I have spent many winters checking out using mostly black powder but also smokeless for the reason of shooting the lesser calibers from .22 to .35 caliber rifles I wanted to use cast bullets in.
Yes smokeless generates a higher pressure then black but it is a progressive burn unlike black powder that gives a fast bump at ignition. If you have used some of the old loading manuals like the Lyman you will see loads for jacketed bullets and also a section for cast bullets. The cast bullets listed where with reduced loads using a fast burning powder that reacted more like the ignition you would get using black. Using smokeless powder with a cast bullet you need that bullet to obturate fast to keep it from getting gas cut, even using a gas check you will get gas cuts using hard or soft alloys, more so with hard. Even when the bullet is of groove diameter the gas will pass past the bullet when it's still in the case in the wider diameter of the chamber before it enters the throat. This is when the gas cuts damage starts.
Black powder with the fast bump it gives the bullet, the bullet obturates before it even clears the case mouth. I have altered cases that would let the bullet shank get pushed through holes at measured distances to find just how far the bullet moves before it bumps up.
Below I have a sample of alloy starting with 1/16 tin/lead from right to left shot with 72 gr of 3F powder and the bullet was patched to tight bore diameter. Bullet from right to left is 1/16, 1/17, 1/18 and the far left is 1/19. The 1/19 you can see a lot of nose setback starting and the grooves are all filled sharp the bottom unlike the 1/16 alloy.
But yes smokeless will obturate even jacketed bullets. There was a extensive article of tests in I think Shooting times or Hand loaders a bunch of years ago about this subject.

Kurt

http://i22.photobucket.com/albums/b302/940Leadpot/th_6e3b303a-e947-4d57-a65c-5fba4cca32cb_zps8ebdgur9.jpg (http://s22.photobucket.com/user/940Leadpot/media/6e3b303a-e947-4d57-a65c-5fba4cca32cb_zps8ebdgur9.jpg.html)

[vzerone]

This subject on how much a bullet obturate I have spent many winters checking out using mostly black powder but also smokeless for the reason of shooting the lesser calibers from .22 to .35 caliber rifles I wanted to use cast bullets in.
Yes smokeless generates a higher pressure then black but it is a progressive burn unlike black powder that gives a fast bump at ignition. If you have used some of the old loading manuals like the Lyman you will see loads for jacketed bullets and also a section for cast bullets. The cast bullets listed where with reduced loads using a fast burning powder that reacted more like the ignition you would get using black. Using smokeless powder with a cast bullet you need that bullet to obturate fast to keep it from getting gas cut, even using a gas check you will get gas cuts using hard or soft alloys, more so with hard. Even when the bullet is of groove diameter the gas will pass past the bullet when it's still in the case in the wider diameter of the chamber before it enters the throat. This is when the gas cuts damage starts.
Black powder with the fast bump it gives the bullet, the bullet obturates before it even clears the case mouth. I have altered cases that would let the bullet shank get pushed through holes at measured distances to find just how far the bullet moves before it bumps up.
Below I have a sample of alloy starting with 1/16 tin/lead from right to left shot with 72 gr of 3F powder and the bullet was patched to tight bore diameter. Bullet from right to left is 1/16, 1/17, 1/18 and the far left is 1/19. The 1/19 you can see a lot of nose setback starting and the grooves are all filled sharp the bottom unlike the 1/16 alloy.
But yes smokeless will obturate even jacketed bullets. There was a extensive article of tests in I think Shooting times or Hand loaders a bunch of years ago about this subject.

Kurt

http://i22.photobucket.com/albums/b302/940Leadpot/th_6e3b303a-e947-4d57-a65c-5fba4cca32cb_zps8ebdgur9.jpg (http://s22.photobucket.com/user/940Leadpot/media/6e3b303a-e947-4d57-a65c-5fba4cca32cb_zps8ebdgur9.jpg.html)

Lead Pot, that's nice work and thanks for posting that.

[Ballistics in Scotland]

Another point not mentioned is a potential pitfall in judging bullet upsetting from recovered bullets. The bullet which accelerates to a given velocity in two feet, is likely to decelerate from it in one foot. If I have correctly understood what 303Guy meant in Post 47, rifling engraving on the transition taper, that shouldn't be affected. But diameters and nose shape may be.

Bone or hard thermoplastic from old electric fittings make pretty good sharp scrapers for removing lead from the outside of firearms.

[Lloyd Smale]

Ill field your question with a yes and no. bottom line is plain old ww will take care of most handgun chores. I never saw a real need to add tin to it. Now if you want the best accuracy a GOOD gun will give you I will say that in 8 out of 10 guns harder will always be better. The alloy I really like is 5050 ww/linotype. But linotype is tough to find anymore so I shoot a lot of #2 alloy and lately have been using a lot of water dropped ww because I have a lot of it and its cheap. I think the point 44man and I were making is its complete bunk that a good gun needs a soft alloy to bump up. Its also complete bunk that harder alloys don't work as well at lower pressures as they do at high pressure high velocity loads. I shot ppc for years using a number of 45 acp 1911s and smith K frame 38s. Just about all my accuracy loads for them ended up being straight linotype. Those loads were just pop gun loads but the harder alloy just plain outshot the softer alloys.

Another bit of misinformation is that harder alloys will lead up a gun if shot at low pressures. If they do you have a gun problem not a bullet problem. Soft alloys might be a band aid for a poor gun or great because there cheap but for serious work ill go hard every time. Another thing to keep in mind is even if you think like me and like a harder bullet it still pays to do some load development. Start with ww and try ww air cooled ww water dropped, #2 air cooled and water dropped and see which your gun likes best. It can be as a big of an accuracy difference as changing bullets or powder. Ill be though that considering your talking 41s, a caliber that is usually done right in most every manufactures guns that harder will be better for you.
So 44man, Lloyd & Doug... say for .41 mag from plinking to hit GCed hunting loads will one alloy work, i.e. COWW + 1-2% tin or will I have to make multiple alloys?

[Lead pot]

If one would really take the time to study recovered bullets from a media that will allow you to see bullets that are not damaged by the sudden impact you would start scratching your head and say how in the h..... did this happen. There is a lot of difference between guessing and speculations to the actual results.
Take these bullets below shot through a .30-30 Marlin with a Lyman #2 alloy mix consisting of 11 lbs WW, 2 lbs 50/50 bar solder and 7 lbs pure lead.
I took and tested a bunch of bullets in the Lever rifle getting ready for a lever action side match at a Gong shoot I was going to and they where all over the paper and some did not even hit the paper at 130 yards. So I had to see what was going on. I shot these bullets below into the fresh snow bank, my favorite recovery media and what I found using one load the bullets where actually longer after they where fired then when unfired and showed some major gas cuts and stripping. A good case of pushing a cast bullet with the wrong powder load. The second photo with a proper light reduced load of Unique the three bullets on the left was my final load that shot well and the bullets stayed together. The first photo is a comparison between the fired and unfired bullets.

By the way, for a .45-70 68 gr of 3F black powder loads a mix of 50/50 old WW Lead will hole the bullet profile as well as 1/17 T/L alloy will. A alloy mix I use and like very much for the PP in loads for the .44-75 Ballard to the heavy .44-90 bn Sharps is a mix of 19# pure lead and one 1# roll of 95/5 solder. 95% tin/5% antimony. Just the 5% of antimony in that 1 pound roll of solder does a fine job holding a bullet profile and fills the grooves completely so you get full rotation.

http://i704.photobucket.com/albums/ww43/Kurtalt/th_IMG_2593_zpswxfhh9s1.jpg (http://s704.photobucket.com/user/Kurtalt/media/IMG_2593_zpswxfhh9s1.jpg.html) http://i704.photobucket.com/albums/ww43/Kurtalt/th_IMG_0542-1.jpg (http://s704.photobucket.com/user/Kurtalt/media/IMG_0542-1.jpg.html)

[vzerone]

If one would really take the time to study recovered bullets from a media that will allow you to see bullets that are not damaged by the sudden impact you would start scratching your head and say how in the h..... did this happen. There is a lot of difference between guessing and speculations to the actual results.
Take these bullets below shot through a .30-30 Marlin with a Lyman #2 alloy mix consisting of 11 lbs WW, 2 lbs 50/50 bar solder and 7 lbs pure lead.
I took and tested a bunch of bullets in the Lever rifle getting ready for a lever action side match at a Gong shoot I was going to and they where all over the paper and some did not even hit the paper at 130 yards. So I had to see what was going on. I shot these bullets below into the fresh snow bank, my favorite recovery media and what I found using one load the bullets where actually longer after they where fired then when unfired and showed some major gas cuts and stripping. A good case of pushing a cast bullet with the wrong powder load. The second photo with a proper light reduced load of Unique the three bullets on the left was my final load that shot well and the bullets stayed together. The first photo is a comparison between the fired and unfired bullets.

By the way, for a .45-70 68 gr of 3F black powder loads a mix of 50/50 old WW Lead will hole the bullet profile as well as 1/17 T/L alloy will. A alloy mix I use and like very much for the PP in loads for the .44-75 Ballard to the heavy .44-90 bn Sharps is a mix of 19# pure lead and one 1# roll of 95/5 solder. 95% tin/5% antimony. Just the 5% of antimony in that 1 pound roll of solder does a fine job holding a bullet profile and fills the grooves completely so you get full rotation.

http://i704.photobucket.com/albums/ww43/Kurtalt/th_IMG_2593_zpswxfhh9s1.jpg (http://s704.photobucket.com/user/Kurtalt/media/IMG_2593_zpswxfhh9s1.jpg.html) http://i704.photobucket.com/albums/ww43/Kurtalt/th_IMG_0542-1.jpg (http://s704.photobucket.com/user/Kurtalt/media/IMG_0542-1.jpg.html)

Well we know that when you size a bullet it gets longer because the metal you are "squeezing in" had to go somewhere. So "squeezing" a bullet into the bore would obviously make it longer. Swaging is the opposite. You are compressing the metal inside a larger die then your initial core of metal so it gets shorter.

Somewhere, not sure here or not, someone mentioned the lube groove or grooves collapsing when their is a lot of bump up. They only collapse as much as the lube can be compressed which isn't much. I'm not saying they don't collapse. Things like the lube being compressed and leaking out is one thing that can cause it, but that doesn't happen a lot either. If you have a lube groove totally collapse you have something seriously wrong.

[Lead pot]

vzerone.
Your right, you cant compress lead but you can make it flow.
I swage a lot of my bullets and if I have a GG bullet and I want to change the profile or bump up to a larger diameter with out collapsing the lube grooves. I fill them with lube and then run them through the swage die. The lube will keep the grooves intact with out squeezing them together.
Those unfired .30 caliber bullets are 1.059" long and after they where shot ended up 1.112" and 1.156" long with wasp waist or hour glass shape, large at the nose and base small in the mid section

[JoeH]

A very interesting discussion with input from lots of people much smarter and better informed than myself. I see, yes, no, maybe, under some conditions, sometimes but "Ballistics In Scotland" is the only one who has brought up an all important point. Whether or not and to what degree "slug up" occurs depends not only on the pressure applied to the bullet base but also on the inertial resistance of the bullet. In effect the bullet base is being squashed between the two forces of pressure and resistance. The resistance is generally represented by the sectional density of the bullet. A bullet long and heavy for its caliber will obturate its base with a rather light, low pressure powder charge whereas a short, light bullet may not opturate even with a much heavier charge and higher pressure.
The long range target rifles of the 19th century, such as the muzzleloading Rigby employed bullets much under bore diameter with a paper patch to bring them up to just an easy sliding fit down the bore. They depended entirely upon bullet upset to fill the bore and engage the rifling. That system worked wonderfully well but only when everything was just right. By "everything" I mean bullet hardness, paper thickness, powder granulation, powder charge, percussion cap strength, ect. Of course they all used bullets of high sectional density and moderate powder charges.
Finding accurate shooting became very much easier when breechloading permitted the use of bullets of full groove diameter and "slug up" was no longer required. Still, when Dr. Franklin Mann wrote his seminal work "The Bullet's Flight" in the early 20th century he found his most accurate loads to employ a bore size bullet which depended on bullet upset to fill the grooves.

[popper]

I shot PC 36+ BHN (.3085") boolits from my 308W @ 2700, compared to mid 20s BHN(.310"), no leading and no difference in accuracy - near MOA @ 100. Same results in 300BO (.3085") PB @ 2100 fps. Hard doesn't cause leading. Apparently bore size doesn't either - for hard cast. I doubt either of these bumped up any - case necks were pretty dirty from neck expansion - only reason I can see for a softer alloy. Well terminal performance is a different reason. Army has done tests to prove jacketed bullets 'bump' up to fill the grooves.

[Lead pot]

Ok. Joe.
Let me ask you this. Does a bullet bump up more from the base forward when the charge goes off or does the nose get setback more from acceleration ????
Using certain alloys I see a awful lot of bullets with the nose setback more then the base is bumped up. :)
http://i22.photobucket.com/albums/b302/940Leadpot/th_IMG_0336.jpg (http://s22.photobucket.com/user/940Leadpot/media/IMG_0336.jpg.html)
I don't shoot smokeless in my black powder cartridge rifle short of a few tests to see how smokeless reacts with bullets compared to using black. There is a great difference between the two using cast bullets.

[vzerone]

Ok. Joe.
Let me ask you this. Does a bullet bump up more from the base forward when the charge goes off or does the nose get setback more from acceleration ????
Using certain alloys I see a awful lot of bullets with the nose setback more then the base is bumped up. :)
http://i22.photobucket.com/albums/b302/940Leadpot/th_IMG_0336.jpg (http://s22.photobucket.com/user/940Leadpot/media/IMG_0336.jpg.html)
I don't shoot smokeless in my black powder cartridge rifle short of a few tests to see how smokeless reacts with bullets compared to using black. There is a great difference between the two using cast bullets.

You're seeing expansion I'm afraid. I can't see a bullet acceleration that great that the bump up is on the nose. Makes me think about really HV j-word bullets in the speed range of say 4000 or over.....that have soft points or hollow points or plastic tips. I believe they would have noticed something strange going on with nose bump up in those a long time back.

[Knarley]

You're seeing expansion I'm afraid. I can't see a bullet acceleration that great that the bump up is on the nose. Makes me think about really HV j-word bullets in the speed range of say 4000 or over.....that have soft points or hollow points or plastic tips. I believe they would have noticed something strange going on with nose bump up in those a long time back.
I think is was in last month or so in the NRA's Rifleman they did talk about the slumping if these plastic tips, that's why Hornady cam up with a new type. Some sort of heat shield. But it was more on the lines of friction from the air resistance than any thing.
Knarley

[vzerone]

I think is was in last month or so in the NRA's Rifleman they did talk about the slumping if these plastic tips, that's why Hornady cam up with a new type. Some sort of heat shield. But it was more on the lines of friction from the air resistance than any thing.
Knarley

I read that Hornady article thoroughly. Their bullet in actual testing wasn't performing to the computer. The problem was occurring at around 300 yards. Then they found out the nose was melting and changing shape. That has nothing to do with bump or slump.

[Ballistics in Scotland]

I think is was in last month or so in the NRA's Rifleman they did talk about the slumping if these plastic tips, that's why Hornady cam up with a new type. Some sort of heat shield. But it was more on the lines of friction from the air resistance than any thing.
Knarley

Well, possibly. But Surgeon-Col. La Garde, who participated in the Thompson-La Garde trials with unfortunate steers in the Chicago stockyards, which led to the .45ACP, dismissed the idea that air friction sterilized bullets in the .30-06 range. He conducted tests which proved that contamination of either the bullet or the charge would infect animals with anthrax - although I think his intention, if any practical relevance was involved, was to prevent infection. A high proportion of American tetanus cases were produced by the blank-firing pistols used on the fourth of July, although that appeared to come from clothing or skin rather than the powder charge, in an age when horse-dung dust was still quite prevalent.

There is more friction at 4000ft./sec. than at 2700, and yet I'd be a bit skeptical of plastic bullet tips failing. If it does, it would surely be far beyond the muzzle. Exposed lead ones make it more plausible, and it just might begin from the first moments of motion. But I don't see why it would be asymmetrical, and deformity of the nose is a lot less harmful to accuracy than base deformity. It doesn't leave a lot of point in making lead points very sharp, though.

I have a great admiration for Dr. Mann's book. Besides being very good on the subject, it is a subject that he got into before anyone else who wrote for the general market in the USA. It has its limitations, though. He is very much co what he calls the putty-plug theory of bullet upsetting - rightly I think, but he mightn't have been quite as convinced if his own preferences and most of his research hadn't run to soft bullets and moderate velocities.

[vzerone]

Well, possibly. But Surgeon-Col. La Garde, who participated in the Thompson-La Garde trials with unfortunate steers in the Chicago stockyards, which led to the .45ACP, dismissed the idea that air friction sterilized bullets in the .30-06 range. He conducted tests which proved that contamination of either the bullet or the charge would infect animals with anthrax - although I think his intention, if any practical relevance was involved, was to prevent infection. A high proportion of American tetanus cases were produced by the blank-firing pistols used on the fourth of July, although that appeared to come from clothing or skin rather than the powder charge, in an age when horse-dung dust was still quite prevalent.

There is more friction at 4000ft./sec. than at 2700, and yet I'd be a bit skeptical of plastic bullet tips failing. If it does, it would surely be far beyond the muzzle. Exposed lead ones make it more plausible, and it just might begin from the first moments of motion. But I don't see why it would be asymmetrical, and deformity of the nose is a lot less harmful to accuracy than base deformity. It doesn't leave a lot of point in making lead points very sharp, though.

I have a great admiration for Dr. Mann's book. Besides being very good on the subject, it is a subject that he got into before anyone else who wrote for the general market in the USA. It has its limitations, though. He is very much co what he calls the putty-plug theory of bullet upsetting - rightly I think, but he mightn't have been quite as convinced if his own preferences and most of his research hadn't run to soft bullets and moderate velocities.

BIS....Hornady noticed the problem when the BC wasn't what the model said it would be at the longer distance, then they started investigating it. Like said they found the nose was melting and that certainly would change the BC very much. I guess you could tie that into accuracy.

Mann was working with BP and flat base bullets...soft alloys too. Kind of a different thing then today's cast bullets with higher velocities, smokeless powders, and gas checks.

[Markbo]

Now all this has brought up another question for me... if you are shooting WDWW coated, do you even NEED a gas check when you kick velocity up past 1500fps?

[vzerone]

Now all this has brought up another question for me... if you are shooting WDWW coated, do you even NEED a gas check when you kick velocity up past 1500fps?

That depends how touch and protective the coating is. Look at paper patched....they reach some very high velocities with just the paper protecting the base and a soft alloy I might add.

[Ballistics in Scotland]

BIS....Hornady noticed the problem when the BC wasn't what the model said it would be at the longer distance, then they started investigating it.

Or they noticed that the market in plastic tipped bullets was getting competitive.