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wind friction----melting bullets?
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<dewman>
posted
In the current issue of Guns & Ammo magazine (Sept. 2002) Col. Craig Boddington states in his article titled "Plastic Fantastic?" (page 32)
"In fast cartridges, exposed lead tips burn off from air friction, but polymer tips to not...."

I have fired thousands of rounds of "exposed lead tip" bullets in "fast cartridges" (22-250, .220 Swift, .257 Ackley Imp. & .25-06) at velocities up to 4,200 FPS with minute of angle accuracy to 500 yards and beyond.

It is my contention that if said melting did indeed occur, such accuracy would be impossible.

It takes a .224, 55 gr. "exposed lead tip" bullet, fired at 3,800 FPS, approximately .27 second to travel 300 yards....at which point it is traveling about 2,500 FPS (Too slow for wind friction to be a factor, heat-wise).

I subjected 10 "exposed lead tip" bullets to an oxy-acetylene torch. It took, on the average, 1.7 seconds for melting to begin. A polymer tipped bullet (Nosler Ballistic Tip) began melting faster that I could work the stopwatch.

I'm not putting down the polymer-tipped projectiles......the best groups I've ever shot have been with that variety.....but....

Common sense, sound reasoning, a little personal experimentation, many years of reloading and thousands upon thousands of rounds down range tell me that "Col." Boddington is full of baloney!

What's your opinion on this subject?

dewman
 
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dewman,
I read the same article, and thought the same thing. Boddington is not full of balogne, he's full of shit. I cannot believe some of the pure unadulterated crap that flows each month from the pages of Guns and Ammo. Elmer has got to be rolling over in his grave.
 
Posts: 8169 | Location: humboldt | Registered: 10 April 2002Reply With Quote
<Reloader66>
posted
The laws of physics are indeed interesting and mind testing. In the sport of shooting accuracy is far more important than melting your projectile tips with blinding speed. You may be interested in knowing that deformed bullet tips have no noticable effect on that bullets grouping ability. The key to a bullets stability is in the base or rear of the bullet. You can fire bullets with damaged points and they will still fly true and remain in the group. Another strange law in physics and bullet flight. Bullets with nicks or minor dents in the base will not fly true and groups will suffer. The fact that you do not believe what you see in print from one information source does not make that information source false. Keep an open mind and learn as much as possible about the laws of physics and our shooting sport. Since you are not an expert in the laws of physics how can you say that information is false.
The fact that you melted bullet tips with your torch will not produce the same effect on that bullet tip as it passes through the air. Colder or warmer air temperatures will produce different results. The exposed lead tip, depending on the core mix will not melt or react the same to a heat source be it the air or your tourch. Your test only proves you can melt your bullet tips with your tourch. Many laws of physics are involved when testing no matter what that test involves.
 
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I got into this discussion a couple of years back with Warren Jensen (owner of Lost River Ballistics). The reason he went to bronze tips on his bullets was the fact that the lead tips of his J-26 bullets melted, and that he had seen evidence that the plastic tips started to melt at long range, as well.

At the time, I was rather skeptical, but I have since seen a number of references that support the notion. One thing to remember, at 300,000 rpm, it doesn't take much softening of the material for serious deformation to begin. FWIW, Dutch.
 
Posts: 4564 | Location: Idaho Falls, ID, USA | Registered: 21 September 2000Reply With Quote
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1. A change in the shape of a bullet nose will affect the striking point of the bullet, if for no other reason than changing its ballistic coefficient. This change will not be as great as with changes, variations, or deformations in bullet bases, but is signficant nonetheless.

2. The temperature rise of the leading surface of the bullet due to air friction that can occur in the half-second between exit of muzzle and striking of target cannot possibly melt lead (or plastic).

3. Temperature rise due to friction is proportionate to the friction, therefore a roundnose (which creates substatially more air friction than a spitzer) should "melt" more quickly and exhibit more deformation. Ain't gonna happen.

4. Although down-range stroboscopic photos of bullets in flight are not common, the few that have been done show no melted tips.

5. Remember when your mechanic used to tell you that the water was circulating too fast in your radiator and that was what was causing your engine to overheat? Same old wives' tale.
 
Posts: 13264 | Location: Henly, TX, USA | Registered: 04 April 2001Reply With Quote
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This has been a popular topic among the slide-rule and labcoat guys for eons. A fairly recent article in Precision Shooting went on for more pages than my attention span would allow, but the highlight was the appearance of "comet tails" on the target paper. This was attributed to a melting lead core. The hows and whys were (are)the subject of great speculation and debate, which I am wholly unqualified to address.

My father (an ordnance physicist) and I (a longtime rifle competitor) would joust for hours over internal and external ballistics. He always won.

Redial
 
Posts: 1121 | Location: Florence, MT USA | Registered: 30 April 2002Reply With Quote
<dewman>
posted
I'm not a physics expert by any streth of anyone's imagination, and didn't mean to imply anything of the sort. My opinion was just that.....my opinion. It's based on my personal experience, and MY reasoning....flawed as it may be.

I have written to several "experts" on the subject....namely, Hornady, Sierra, Speer, Lazzeroni Arms, Sandia Labs., Ames Research,
Nosler and Dr. Ruprecht Nennstiel of Wiesbaden, Germany concerning this burning issue.

To date, I have received three responses.....(Rick Machholz of Sierra, John Lazzaroni of Lazzaroni Arms and Dr. Nennstiel) all supporting MY opinion. Although I'm NOT an expert on physics, they certainly should be consider such.

I don't know how the question could be answered, once and for all, other than actual photos of the bullet melting in flight.....and, as far as I know, there are none showing such.

But, it's great hearing all the opinions posted here.

"As long as there is an open mind, there will always be a frontier."

dewman
 
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Hey dewman, It seems to me this is fairly easy for anyone that has a bit of time, a few extra bullets and a long distance Range to run a short test on their own.

Rather than get into the discussion with an answer based on experience(I've done this), let me suggest a method to resolve it for yourself.

All you need to do is fire about 18 Lead Tipped bullets and 18 that you have removed the Lead Tip on with a knife or file. Shoot at two targets placed 400yds away or beyond. Alternate shots between one with a tip and one without a tip so as to minimize the effect of the wind. Do it when the wind calms at sunrise or sunset to get the best conditions. Ignore the three highest and three lowest Points of Impact on each Target. Then "average" the distance below a horizontal line passing through the aiming point for the remaining 12-shot groups on each target.

The distance is important so it is easier to detect Point of Impact variance and the number of shots is important to make the test results significant.

Best of luck to you guys. You can sure learn a lot by just doing a bit of shooting at 400yds and beyond.
 
Posts: 9920 | Location: Carolinas, USA | Registered: 22 April 2001Reply With Quote
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Hmmm. If you could "catch" a bullet after a long range flight, you could (in theory) measure the weight loss (or non-loss) of a tip.

I wonder how you would go about construction a "non-deforming bullet trap"? Dutch.
 
Posts: 4564 | Location: Idaho Falls, ID, USA | Registered: 21 September 2000Reply With Quote
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Dutch:

It would be a bit of trouble, but what is that for a confirmed bullet experimenter? Take a farm pond a 1000 yards or so away, and place a bed sheet weighted down in 3 or 4 feet of water and fire away. Should be fairly easy to recover the bullets in the same shape they were in flight.
 
Posts: 17099 | Location: Texas USA | Registered: 07 May 2001Reply With Quote
<Reloader66>
posted
It should be noted that as the bullet moves down range that projectile is consistantly losing forward momentum. That loss of momentum is determined by the weight and shape of the bullet and the maximum velocity it left the bore. If the lead or plastic bullet tip were going to melt it would seem logical to me that it would melt the first 15 feet of travel leaving the muzzle. The highest velocity attained by the bullet is the first fifteen feet of travel as the bullet exits the muzzle. Every inch it travels after that, the bullets forward velocity is decreasing. Since the bullet is constantly losing forward momentum air friction against that bullet tip would diminish.
It was long believed that the 220 swift would melt 40 grain bullets cores with a velocity of over 4200 FPS at the muzzle. With over 45 years experience in the shooting sport I know of no bullets that melted in flight. Some bullet makers today state on the package the maximum velocity that bullet should be driven. Also the twist rate that bullet will tolerate or stabalize. It does not state that the bullet would melt in flight. Those directions are in regards to the jacket thickness not the lead core. Excessive velocity causes accuracy to suffer in any cartridge I have every tested.
 
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Don't the rounds that tanks fire, depleted uranium projectiles that are encased in a sabot, or 'silver bullets' as I have heard them called burn from air friction enroute to their target?
 
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<Made in Sweden>
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I guess Mr Bell was right when he thought lead tipped bullets soiled the barrel... another reason to use solids!!!
 
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I've found in my 22-250 Seirra's 55gr med. velocity spitzer(lead tipped) gives me some nice groups out to 300yds, haven't tested any farther. I don't give a rat's banana if the tip melts or not as the bullet is still accurate and performs well on game. Maybe I'm not intellectual enough but as long as the bullet is doing what I want it to do why worry about it?
Edit: I don't read gun rags either.
my 2 cents,

Chris

[ 08-09-2002, 17:18: Message edited by: CISCO ]
 
Posts: 200 | Location: Belle Plaine, IA USA | Registered: 09 July 2001Reply With Quote
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Reloader66, no, I don't think so. At all. The resistance of a bullet in flight is something like 60 G forces, and exposure to that kind of resistance has to result in heating. Even if the bullet drops the the speed of sound (1,000 or so yards out there), the forces would be quite high, like 20 G's (MAYBE?).

Plus, the jacket itself MUST pick up quite a bit of heat from the friction with the bore during firing. So we have a pre-warmed projectile exposed to exceeding high air friction. I don't have the skills to do the math, but I would not at all be surprised to see that these bullets heat up far beyond the lead melting point. FWIW, Dutch.
 
Posts: 4564 | Location: Idaho Falls, ID, USA | Registered: 21 September 2000Reply With Quote
<CatShooter>
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The MAJOR flaw in "Col." Boddington's statement is this... the melting point of plastic is LOWER than lead by about 300 degrees (lead melts at around 750, plastic melts at around 350).

The "Col" is full of silly nonsense and made up stuff, just to get an article in by the editors deadline... not the first time by any means.

This is an old wives tail that has gone on for 50 years.

It HAS been studied to death in the past, and answered to completion.

IF, the tips were melting, you would see a uniform gray ring around every bullet hole in a white paper target. And recovered bullets would have gray streaks of lead on the ogive, where the "melted lead" flowed over the bullet... none of which happens.

The comet tails metioned are from jackets that are too thin for the rotational speed, and split along a rifling indentation, and the lead is being spun out.

If the tips (or the cores) melted, we would never have acheved the levels of accuracy that modern bullets have.

CatShooter.

[ 08-11-2002, 14:40: Message edited by: CatShooter ]
 
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Heh... one of my favorite gunshop crank stories, here on the Internet!

I won't deny that there is some possibility/probability of there being some serious heat due to air friction. But some people take it just a little too far...

Went into a pawn/gun shop one day to pick up some .223 ammo. Owner asked me what I was going to shoot w/ the stuff. Told him prairie dogs and targets, and we started discussing some other calibers. Good, he says, it sounds like yer a shooter that knows what works (imagine a really bad drawl here). Some folks come in here complaining that they just can hit anything out there 400-500 yds w/ their .223s, and they just don't understand that its 'cuz the bullets, well they just melt due to the air friction, and there just isn't anything left of them (he even said he'd made sure to train his other clerks to tell said customers this). Thats why the .223 was only good for 300-350yds, cuz them bullets just melted beyond that. I looked at him, wondering just what in the hell he was on, and did I really look that damn dumb? He was serious as a heartbeat, though. Didn't have much answer when I asked how then were the Service Rifle and DCM Hi Power shooters using .223s out to 600 and 1000 yds. 'Probably some special military tungsten bullets or some such. Maybe titanium, like in that there Blackbird plain, ya know?' (BTW, I am aware of the very expensive exotic material bullets. Just don't think thats the reason for them ;p ) Oh, boy. Well, then, if the bullets from a .223 do melt beyond 350yds, then, why isn't a .22-250 or .220 Swift only say, a 250yd cartridge, since the bullets are supposed to be going a lot faster, aren't they? Shouldn't they melt sooner. Hmmm... didn't have much of an answer for that one.

Hell, this guy even tried to peddle me this same song-n-dance another later date. Must have forgotten that I'd told him he was crazier than a pet coon and to go piss up a rope the first time. Don't think he forgot after the second time.

Talk about a corner of the gene pool in dire need of chlorination.
 
Posts: 341 | Location: Wenatchee, WA | Registered: 27 February 2002Reply With Quote
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whoops. wrong click.

[ 08-14-2002, 14:17: Message edited by: milanuk ]
 
Posts: 341 | Location: Wenatchee, WA | Registered: 27 February 2002Reply With Quote
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Well, them there .223's must be the ultimate in safety bullets. They just go away after about 300 yards. Now I can stop worrying about backstops; what a load off my mind.
 
Posts: 13264 | Location: Henly, TX, USA | Registered: 04 April 2001Reply With Quote
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milanuk - A quick way to win this illogical argument next time it comes up is to ask the mental wizard to stand behind this claim - literally. After all, the bullet will certainly melt before it hits him, right?

Gun Magazine Editor Mantra - �Make shit up, folks will read anything and believe it�....
 
Posts: 10780 | Location: Test Tube | Registered: 27 February 2001Reply With Quote
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One call to Hornady will help with part of this. They state at 2600 FPS that soft lead tips do indeed melt. One call will get you the answer. 1-800-338-3220. We start these bullets from a standing start to several thousands of feet per second, the projectile is heated to temperature far in excess of the melting point of any of it's components and send it spinning at several hundreds of thousand of feet per minute. All of this in just nanoseconds. Something has to give.

Nosler BT's and Hornady V-Max bullet tips are not plastic, they are made of a polymer product, higher melting point than lead. Ever wonder why nylon seals will wear a groove on a crankshaft without melting?

[ 08-14-2002, 23:07: Message edited by: Allen Glore ]
 
Posts: 1058 | Location: Lodge Grass, MT. Sitka, Bethel, Fort Yukon, Chevak, Skagway, Cantwell and Pt. Hope Alaska | Registered: 24 June 2000Reply With Quote
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Interesting thread. I tend to hold with the crowd who thinks this "melting tip" is mostly bunk. Have we forgotten cast bullets...where the ENTIRE projectile is lead? These bullets are sometimes loaded up well over 2,000fps and nothing seems to melt.

I've gone out beyond the berms and recovered too many fired bullets to believe this stuff. I'm way far from convinced any of this takes place.
 
Posts: 19677 | Location: New Mexico | Registered: 23 May 2002Reply With Quote
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Leading of the barrel is caused by melting lead. Cast bullets are also a little harder of an alloy. Heat treated and sometimes water quenched to bring up the hardness. And nobody has been able to give emphatical proof that it doesn't happen.
 
Posts: 1058 | Location: Lodge Grass, MT. Sitka, Bethel, Fort Yukon, Chevak, Skagway, Cantwell and Pt. Hope Alaska | Registered: 24 June 2000Reply With Quote
<Greg H>
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Allen Glore,
Thanks for taking the time to find the facts. Noone seems to notice when facts do not support fiction. I guess we all know the answer .
Thanks again,
Greg H
 
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I started this very same discussion on a couple of different forums several months ago. The nay sayers still can't prove what I said was wrong. And as at the other forums, people here also steered this away from BULLET TIPS to turn it into BULLETS melting or burning. Some should learn to comprehend what they are reading.
 
Posts: 1058 | Location: Lodge Grass, MT. Sitka, Bethel, Fort Yukon, Chevak, Skagway, Cantwell and Pt. Hope Alaska | Registered: 24 June 2000Reply With Quote
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Rather than a bunch of conjecture and guessing regarding what is happening to bullet tips, a few high speed photographs of �actual� melting tips would speak volumes. This is really no big deal to accomplish. Hyper-speed photography is utilized extensively in the development of military weapons. It seems simple enough to blast a few small caliber bullets down range and take a picture of one.

In actuality, who gives a rip if tips melt or not. This means nothing to me because I achieve the level of accuracy I need from my LR target/varmint guns. Furthermore, I have never seen any proof that tips melt. In fact, every high speed photograph I have ever seen of a bullet clearly shows the tip fully intact and healthy. This would seem to be the norm, rather than the exception. With the millions of hours of ballistic tests which have been conducted over the past few decades, it would seem reasonable that someone would have made a big deal about melting tips. Maybe this little phenomena simply slipped through the cracks.

Another consideration is BC. If tips are melting, you can be assured that the BC of the bullet is continually altered throughout its flight. All long range BC calculations are directly proportional to velocity decay and the physical dimension of the bullet remains the constant. Alterations in BC during flight would be clear proof that �something� is physically altering the bullet - i.e. melting tips. Again, I have never seen any BC correlation that would substantiate such a claim.

Most magazine writers offer lots of opinion and not much substance. I guess they do serve at least one purpose - they give us lots to argue about. It�s always more difficult to argue against proof and facts, I guess we won�t need to worry about that any time soon.

[ 08-15-2002, 06:14: Message edited by: Zero Drift ]
 
Posts: 10780 | Location: Test Tube | Registered: 27 February 2001Reply With Quote
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quote:
Originally posted by Allen Glore:
Leading of the barrel is caused by melting lead. Cast bullets are also a little harder of an alloy. Heat treated and sometimes water quenched to bring up the hardness. And nobody has been able to give emphatical proof that it doesn't happen.

Allen - You comparison of cast bullets leading a barrel with the tip of a bullet "melting in flight" is ridiculous, my friend. [Smile] In one instance you are claiming the tips melt away from AIR FRICTION whereas with cast bullet leading it is a TOTALLY different cause...as any cast bullet shooter will be happy to enlighten you. Flying merrily thru the air is not the same as METAL TO METAL CONTACT. If you don't believe me, drain all the oil out of your car engine and try driving down the highway as fast as you can go. [Eek!] Let me know which melts down first, you car or the engine.

As if metal to metal contact isn't enough, improperly sized cast bullets allow 4,000+ degree gas to blow by them as they slide up the barrel. This "gas cutting" can lead to a hell of a lot of leading as well. I got a sneaking suspicion cast bullets are NOT your field of expertise. [Roll Eyes]

Your comparison of these two issues is certainly the old "Apples VS Oranges" syndrome.

As for the "emphatical proof" you are hungry for, let me suggest you go out to a good firing range and spend some time down range examining spent bullets, cast and otherwise. I think it will be very educational. I've probably collected several hundred pounds of fired bullets, cast and otherwise, and I've yet to find a melted tip on anything.

I would remind you lead is a very poor conductor of heat and the whole "life span" of the fired projectile from ignition to impact is generally measured in FRACTIONS of a second. You are suggesting this bullet goes from say 60 degrees farenheit to over 100 times this temperature in a quarter second just from traveling thru 200-300 yards of air? [Big Grin]

Sorry. This is a bit too far fetched for me to swallow. I ain't trying to be ornery. Just saying it doesn't make a lick of sense NOR does it jive with my 46 years worth of experience making and firing and chasing bullets around the countryside.

As someone suggested, I'll believe this when I see photographic evidence of bullet tips melting off and streaming back in flight. I don't give a flip WHO claims it happens in what gun magazine. He may have been out drinking with airline pilots the night he got the inspiration for this tale. [Wink]

[ 08-15-2002, 05:25: Message edited by: Pecos45 ]
 
Posts: 19677 | Location: New Mexico | Registered: 23 May 2002Reply With Quote
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Pecos, your reply is so well-put that I take back all of the bad things I've said about your Bushnell scopes.
 
Posts: 13264 | Location: Henly, TX, USA | Registered: 04 April 2001Reply With Quote
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quote:
Originally posted by Stonecreek:
Pecos, your reply is so well-put that I take back all of the bad things I've said about your Bushnell scopes.

Repentence is good for the soul, Stone. [Smile]
 
Posts: 19677 | Location: New Mexico | Registered: 23 May 2002Reply With Quote
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Bullets aren't in the air long enough to melt.
 
Posts: 8351 | Location: Jennings Louisiana, Arkansas by way of Alabama by way of South Carloina by way of County Antrim Irland by way of Lanarkshire Scotland. | Registered: 02 November 2001Reply With Quote
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quote:
Originally posted by CatShooter:
The MAJOR flaw in "Col." Boddington's statement is this... the melting point of plastic is LOWER than lead by about 300 degrees (lead melts at around 750, plastic melts at around 350).

Duh, I think Cat just blew the great (in his own mind) Boddington out of the water with this argument. [Big Grin] If the plastic tip melts at a lower temp than the lead (which is true) wouldn't putting the polymer tip on a bullet be the worst possible thing to do? Wouldn't we start seeing "polymer coating" in our barrels instead of leading?

This whole article by Boddington is ripe with stupidity.

Copper is a REAL good conductor of heat. If bullets get that hot in flight from air friction, why doesn't the WHOLE lead core melt and sling out? Duh? Answer - NONE of it has much of a temperature change.

If you're watching Boddington, here's a BIG horselaugh for you, buddy. [Big Grin] [Big Grin]
 
Posts: 19677 | Location: New Mexico | Registered: 23 May 2002Reply With Quote
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quote:
Originally posted by Dutch:
One thing to remember, at 300,000 rpm, it doesn't take much softening of the material for serious deformation to begin.

DUTCH - Where in the WORLD did you come up with this 300,000 rpm nonesense? I think the only thing spinning that fast is your imagination.

If we have a 1-10" twist, (which is a pretty FAST TWIST!) this means the bullet makes 3.6 revolutions PER YARD. At 100 YARDS, the bullet has revolved 360 times. Over the course of a 500 yard shot, the bullet has only revolved 1,800 times, my friend. My point being a bullet in flight is hardly the "whirling dervish" you seem to think it is. Over the course of its downrange flight a bullet is actually rotating very liesurly. [Smile] Think about it.
 
Posts: 19677 | Location: New Mexico | Registered: 23 May 2002Reply With Quote
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quote:
Originally posted by Dutch:
Reloader66, no, I don't think so. At all. The resistance of a bullet in flight is something like 60 G forces, and exposure to that kind of resistance has to result in heating. Even if the bullet drops the the speed of sound (1,000 or so yards out there), the forces would be quite high, like 20 G's (MAYBE?).

Dutch, are you just TRYING to be misinformation junction on this thread or what? [Confused]

A "G force" is a function of either ACCELLERATION OR DECELLERATION. (Or you can induce a G force by changing direction rapidly like when an airplane turns or in a centrafuge.) But for bullets it's accelleration and decelleration.

Once the bullet leaves the barrel of a rifle there is ONLY decelleration...and at such a liesurly rate that YOU could probably ride the bullet down range with no ill effect. Where you come up with your G force figures I cannot imagine! Granted the initial accelleration down those first 24" of the barrel are pretty substantial, but you aren't going to get enough "air resistence" in 24 inches to melt an snow cone.

Your theories hold less water than Boddingtons!
 
Posts: 19677 | Location: New Mexico | Registered: 23 May 2002Reply With Quote
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I said it before, and I'll say it again, Boddington is full of shit.
 
Posts: 8169 | Location: humboldt | Registered: 10 April 2002Reply With Quote
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Pecos45,

The G forces in the bullet's slowing down are incredible.

To take an extreme, consider the 220 Swift leaving the muzzle at 4000 f/s.

I don't have a ballic program opne, but this will be close enough.

Let us say at 100 yards it has slowed to 3500 f/s.

To ravel that 100 yards will have taken about .08 seconds. So it has "braked" by 500 ft/sec in .08 seconds.

Now V = U + AT

Thus 3500 = 4000 + A*.08

Thus A*.08 = -500

Thus A =-500/.08 =6250

6250/32 = 195 Gs

Mike
 
Posts: 7206 | Location: Sydney, Australia | Registered: 22 May 2002Reply With Quote
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Like I said, Mike, Dutch could probably RIDE that bullet down range. [Big Grin]

No, seriously, I don't claim to be a hair on a mathematicians butt...but I know the lead doesn't sling out of the bullet from the decellaration, even if it is 195 G's as you propose. And obviously it doesn't blow out the back end of the bullet from the Accelleration, which has got to be a zillion times more than the Decellaration. In fact with the decelleration you claim to have calculated for us here, it makes one wonder how the world the little polymer tip stays attached. After all, it's just sort of stuck on.

As some one stated above, Boddington is full of shit and probably just wrote this silly piece either to stir up a commotion or because he really IS an idiot. Which, I don't know or care.

Ballistic tips or silver tips etc don't sling off from decelleration OR impact quite often. I've yet to ever find a spent bullet with lead streaks from a melt down or anything else. Boddington's story sounds real dramatic until one engages one's brain...and then a smile creeps over one's face. Silliness. [Smile]
 
Posts: 19677 | Location: New Mexico | Registered: 23 May 2002Reply With Quote
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Pecos,

Back in the late 60s we use to use 219 Zipper Improveds a lot in Austrlai with 50 grain Hornady SX bullets.

Frequently at the range, you would see waht bI would describe as like a silver sheen appear in the air about halfway or 2/3rds down to the 100 target.

It was always thought that air friction was literally sanding off microscopic biths of lead and because there was no lead oxide on those bits, they shone in the sun.

Off the topic, but when you spotlight shoot you often see an ornage streak go down and believe it or not, that is supposed to be the spotlight shining off the base of the bullet.

As to the 195 Gs and ballistic tips, remember that a couple of things contribute to them not popping out. Firstly would be air pressure. Secondly, I think if you attached a weight that was 195 times heavier than the ballistic tip it would not pull it free.

Mike
 
Posts: 7206 | Location: Sydney, Australia | Registered: 22 May 2002Reply With Quote
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Funny thing to discuss!! [Smile]
I have seen a tip recovered from a Mulie shot with a .270 and 150gr. ballistic tips. If it had melted in any way we wouldn't have found it. Thats a fact I have personal knowledge of.

If the lead melts off in flight then we are using a lot more hollow points for taking game than anyone ever proposed! [Big Grin] I do know the Sierra HPBT kills deer well enough, but now the highly regaurded Nosler Partition is really a hollow point? [Big Grin] [Big Grin] [Big Grin]
I have recovered slugs from trapping them in water and found no trail from liquid lead adhered to the jackets. When cooling moltent metel quickly I would expect to see some of this at least.
As for the Hornady SX bullets I have had them come apart in flight. In both a fast twist .223 and from a .22-250. I could slow them down in the .22-250 and they stayed together but whats the point? Never did find them a loading in the fast .223 barrel but they worked great in a Contender 14" with a standard twist rate. Hornady says the fragile jacket it to blame and not the heat.
If the melting tip theory were true would it be most evident in something like the .22- 50 BMG ? I would like to see the photos.

Crowrifle, the depleted Uranium has such a high density it penetrates armour. If it were burning up in flight wouldn't it be to soft and just splatter? My way of looking at it anyway.
 
Posts: 2376 | Location: Idaho Panhandle | Registered: 27 November 2001Reply With Quote
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Mike,

Do you have the math skills to convert the Joules created by a 195 G decelleration into degrees of heat gain by the bullet?

Pecos: If the bullet makers say it is so, the military says it is so and the math says it is so, and you say it isn't, who do you think I'm going to believe?

The laws of physics are not suspended, just because something happens quickly. If a bullet leaves the barrel with 1,000 ft/lbs of energy, and it is left with 500 ft/lbs of energy a quarter second later, WHERE ELSE DO YOU PROPOSE THAT 500 ft/lbs OF ENERGY GOES, if it doesn't get converted to heat? Magic?

Of course the energy goes into the bullet (and the air), and not the whole bullet either. It happens too fast for heat to conduct from the bearing surface to the inner part. So, the energy IS converted to heat, and the majority of it IS concentrated on the leading edge of the bullet (that's where the friction is).

Now, in classic "back of the envelope" fashion, we know a rifle is about 30 to 50% efficient in converting powder chemical energy to bullet speed energy. (physics types will please forgive me for the terminology....) Suppose we lose half of that energy during the period of bullet flight under discussion. Half of THAT goes into the air, half to the bullet. The question becomes:

A 50 grain load of powder behind a 100 gr. bullet (easy math [Wink] ), 30% efficient, divide by half to represent the lost energy of the bullet, divide by half again to allow for the energy lost to the air: 50/3/2/2 = 4.something grains of powder. So, in essence, will the energy in 4 grains of smokeless powder melt the lead tip of a bullet? I've melted enough lead as a kid to say with a high level of confidence: yup.

If you want to pick nits, the critical amount of energy is only that amount that softens the lead enough for the lead to spin off under 300,000 rpm.

BTW, I collected a number of fired 55 gr. ballistic tips from snow this winter, and no signs of melting was found at 200 yards. This winter, I will repeat that experiment at 400 to see if there is a difference. FWIW, Dutch.

[ 08-16-2002, 18:02: Message edited by: Dutch ]
 
Posts: 4564 | Location: Idaho Falls, ID, USA | Registered: 21 September 2000Reply With Quote
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Dutch,

I will dig around a bit on the weekend.

The tricky part (at least at my level [Big Grin] ) is that much of the heat goes to the air.

In fact Joule's experiment if I remember correctly consisted of rotating a paddle wheel or propellor in water and then measuring the increase in temperature of the water so as to derive an equivalent for conversion between mechanical energy and heat energy.

In this case, I guess we could call the bullet the paddle wheel and the air the water.

In real day to day terms the bullet is like an air cooled motor.

Mike
 
Posts: 7206 | Location: Sydney, Australia | Registered: 22 May 2002Reply With Quote
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