Bullet Blow Ups

[fredo]

My thoughts: Thin enough jacket, high enough velocity AND a tight enough twist. The result is that white puff down range.
My knowledge of annealing bullets is zero. (actually never heard nor thought about it at all)

Basically, this.

What we're seeing is how super heavy for caliber bullets & the fast twist barrels they require to stabilize them, have begun to 'hit the wall' with regard to their practical use...

'End arounds' to maintain bullet integrity range anywhere from using specialized gain twist barrels & various land profiles, to simply using thicker, harder jacket material. All fascinating stuff to ponder, but...to what end?

Are these super heavy bullets allowing a significant enough ballistic advantage to where risking bullet integrity is worth the reward? That question obviously needs answered on an individual basis, just throwing it out there, for consideration...

From where I'm sitting, I want to first establish an attainable MV for each bullet, from a given cartridge, in order to determine ballistic superiority of one, over another. Simply stated, if a super-heavy bullet can't be pushed fast enough to tangibly beat a lighter (faster) bullet, then what's the point of even bothering?

These super heavy for caliber bullets had better show a marked increase in performance in order to justify the risk of suffering premature failure. If that advantage can't be determined, then arguing why/how those super heavys are 'blowing up' only serves to define what "the wall" is made of, rather than simply avoiding hitting "the wall" in the first place...

Don't get me wrong, I'm all about 'pushing the envelope', as it is a driving force behind innovation! But, I also try to view things from a practical perspective. There needs to be a clearly defined & practical advantage to going super heavy in bullet weight, vs. finding a more harmonious pairing of MV & b.c. that provides performance without undue risk of failure...

 

[geo.ulrich]

George what do think of this?
Have you ever eaten directly out of a container of ice cream. The outer layer melts. During the core seating process the jacket is expanded thus a mechanical bond between core and jacket. Melt the lead and it's going to flow somewhere. The cause, the jacket returning to its original drawn diameter.
I tend to think that would have a detrimental effect on performance.

Dave , I am not annealing bullets but jackets, well certain ones before we make them. I am in agreement on finished bullets its a bad idea unless the bonded core is where they are going but that's a different discussion.

 

[geo.ulrich]

The lead core and copper jacket will rotate at different speeds if the bullet is not formed correctly.
Bonding of the 2 are by pressure, solder or bead blasting the inside of the jacket. Some custom bullet makes use vinegar to etch the inside of jacket , so it grips better.


A loose core + spinning friction may make the core liquid. No a good thing for accuracy.

Cast bullets are heated in an oven, then placed in cold water . They increases in hardness , as long as 2% or more antimony is present in the alloy.
A cast bullet shrinks in the mold as it cools. The % of antimony content has a direct effect on diameter. The higher % of antimony, the larger the bullets diameter.

So, if you heat a copper alloy jacketed lead core bullet to the correct temperature, long enough and cool in water, the lead core will harden and the jacket will soften.

The final process would be sizing of the bullets in a die.. If the bullet is sized down more than .005" the lead core may become loose inside the jacket. Brass springs back more then lead.

Bead blasting the inside of jackets really. I have been making bullets for 35 yrs. and that's a new one. how do they keep media off outside. vinegar was used for etching cores not jackets not such a good idea either it creates a boundary of oxidation between core and jacket. for custom bullet makers 1/2% antimony is about all you will find I like 1% but unless you plan on buying a special run that's not happening. sizing bullets down AFTER heating them is really a bad Idea soft jacket loses mechanical grip and core will slip. If bullet is sized down more then .00005 to .0001 jacket will spring back and mechanical grip will not be enough. and yes the zeros are correct....

 

[Webster]

243winxb's response was what I was looking for in another thread - this appears to be annealing of bullets. Just keep on asking sometimes helps, at the risk of appearing to be slow - I sure did not find what I was looking for in that thread. My attached link gives more info on annealing bullets.

I also was curious as to where lead was produced in Missouri, a region with large galena deposits. A subsequent search showed a huge lead recycling facility near Bixby Missouri complete with rail access and large capacity electrical power lines leading directly into the plant. Apparently, this plant recycles lead batteries instead of smelting operations using galena. Hopefully, lead production might be done by some wet chemical process that would reduce pollutants to acceptable levels - thus keeping the entire operation within the USA (jobs). A view of that plant's operations showed ingot forming from melted lead and mentioned mixing other metals that I would guess might be antimony.

My thoughts are that during the bullet forming operation the bullet jackets might be excessively work hardened. I am also guessing that real long pointy bullets might have more yaw than stubby bullets and a combination of yaw, huge rpms caused by fast twists, high velocities and brittle jackets might result in bullet disintegration a short distance from the muzzle. My 53 grain Hornady hp fb bullets as best as I remember were longer than the 52 Sierra bullets and were not stabilized adequately as shown by bullet profile holes at 100 when shot from a 1-14 .22-250 - that is the bullets that did not blow up.

Taking a look at 10X magnification of various sectioned pointy hollow point Berger bullets shows shallow grooves on the outside of the bullet leading to and converging at the point. Looking at the inside of a Sierra 107 grain 6.5 bullet (large void in front of core) shows a series of shallow flattened areas separated by grooves leading to the point, same for the Berger bullets. My guess is that the grooves might be deeper than seen (expansion cracks?) and could indicate areas where the jacket might fail. All this is from my casual observations as an amateur having no insider info.

The OP of the original thread apparently was shooting 142 Sierra MK's from a 6.5-.284. Another member observed a problem with 162 Amax's from a 7 RUM. Another indicated problems with 90 grain .224's. All long pointy bullets.

I think the very short transit time a bullet spends inside the barrel would prevent lead core melting. Various bullets having lead exposed at the base like the 100 grain .257 Nosler partitions I fired from .257 AI and .25-06 did not show melting when the bullets were recovered from various dead animals. I quit the .25's and now shoot 6.5's.

How dirty is dirty? Would extreme jacket fouling result in jacket failure considering the contact area of bullet and barrel is the shank of the bullet, the area having the least work hardening.

Quit worrying about a problem that doesn't exist and keep shooting.

 

[geo.ulrich]

or a problem that you can not fix

 

[Webster]

or a problem that you can not fix

I believe the OP didn't say he was having bullets blow up. He just wanted to learn what may cause it.

 

[fyrewall]

Still here.

Some thoughts - do long and heavy for caliber hunting bullets blow up when shot at velocities of about 3000 or more?; do long and heavy for caliber bullets, of any jacket type, hunting or match, shot from 6.5 CM or 6.5X47L at "safe" MV's blow up?; upon buying bullets for some "rocket type 6.5" such as a 26 Nosler would it be a good idea to avoid the long pointy match types? (can't fix it?)

I am unable to get the .204 40 VMax (3750 fps, 11 twist), .224 53 Vmax (3750 fps, 7.7 & 8 twist), .243 87 Vmax (3300 fps, 8 twist), and .264 95 Vmax (3350 fps, 8 twist) to blow up without hitting some target. Sg values for all except the .204 40 Vmax 11 twist are large, some approaching 3.7. Accuracy is surprisingly good for relatively short bullets fired through high quality (mirror bright lapping) barrels having excessively fast twists for any bullet with the exception of the .204 40 grain.



The attached screen shot was taken from the Hornady tech. stuff - it shows pitch & yaw for some bullet, probably some 140 grain or heavier 6.5 ELD match type. I am thinking the combination of high velocities, yaw-precession, fast twist, heat, and air resistance might promote any weaknesses in the bullet ogive area to cause a blow up.

George might have a good point - at least there might not be a cost effective way to fix the problem.

I will be content to shoot 130's from my 6.5X47L.

 

[243winxb]

Bead blasting the inside of jackets really.

Yes , really. vapor blasting media--glass beads, BT8

The invention provides a technique for vapor blasting the interior of regular production bullet jackets prior to lead seating. The controlled vapor blasting significantly increases the surface roughness of the bullet jacket interior. As a result, the formed bullet has greater adhesion between the bullet jacket and lead core.

http://www.freepatentsonline.com/4660263.html

Assignee:
Olin Corporation (Stamford, CT)

 

[243winxb]

. If bullet is sized down more then .00005 to .0001 jacket will spring back and mechanical grip will not be enough. and yes the zeros are correct...

Go here and look it up. Resizing finished bullets . http://www.corbins.com .005"

or a problem that you can not fix

Inventers have made millions fixing problems.

 

[geo.ulrich]

Yes , really.

http://www.freepatentsonline.com/4660263.html

Assignee:
Olin Corporation (Stamford, CT)

You might want to reread that patent, where it says sand blasting has Not been tried just vapor blasting, Funny I'm maybe two miles Olin/ Winchester in East Alton and have done tons of work for them kind of was a main customer. Been in all sections of the plants and have never, ever , ever seen this process in their making bullets....there are tons of patents floating around does not mean they are being utilized....

 

[geo.ulrich]

Go here and look it up. http://www.corbins.com .005"

There you go Corbins the place to go for match grade dies ,,,,,I'll stick with the 60 or so I.B.S and N.B.R.S.A benchrest records shot with my process and dies thanks..Perhaps the 22 hulls can be used to shoot a few records....L.M.A.O.

 

[243winxb]

http://benchrest.com/showthread.php?57965-Bullet-core-stripping

A good read on bullet making.

geo.ulrich, remember this one?

 

[geo.ulrich]

There has been a bunch of them they all kind of run together. funny revisiting a whole slew are customers...

 

[Dusty Stevens]

There you go Corbins the place to go for match grade dies ,,,,,I'll stick with the 60 or so I.B.S and N.B.R.S.A benchrest records shot with my process and dies thanks..Perhaps the 22 hulls can be used to shoot a few records....L.M.A.O.

Seems like everytime somebody wants to start making bullets somebody throws corbin out there. Marketing genius i guess cause evidently it pops up on every google search for “custom” or “match grade” bullets

 

[243winxb]

vinegar was used for etching cores not jackets not such a good idea either it creates a boundary of oxidation between core and jacket.

Your correct, i had it wrong.

I better stick to making cast bullets.

 

[geo.ulrich]

It etchs the cores pretty well, used to be common place. I core seated etched, oiled with a very small amount and clean dry cores . Then drilled a small hole in the bottom of jacket and used a scale on a press to see which one held the best, guess which it was. I will give a hint no barrier layer between core a jacket is best....Can't fault someone that doesn't know

 

[fyrewall]

forever struggling …. vinegar contains acetic acid and exposure to which with copper, will form green-blue junk or vertigris (a useful pigment). Acetic acid exposure to lead combined with heat and an oxidizer will make for some type of lead oxide (a nasty poison but useful pigment). Cleaning any lead oxide from the core would result in a etched lead surface. Don't think any of this junk between core and jacket would glue core and jacket together. Should a lubricated core be stuffed into a jacket the jacket spring-back would help to hold everything together. Electro plating the core with copper would probably be the best.

For short jacketed bullets, especially larger caliber bullets, would the outer jacket having bigger radii be subjected to large rotational forces and the underlying lead core be sheared away or would the entire works be rotated in unison? My casual observations show no slippage caused separation between core and jacket.

I always wear nitrile gloves when working with lead - bullets, primers.

 

[geo.ulrich]

No it should have less rotational forces if the correct twist is used. ie. 925-1.00 jackets only require a 17-20 twist to stabilize. on the further end I have used .850 30 cal. jackets and they were stable with a 24" twist...as long as cores are seated correct once engraved there should not be any slippage. the rifling engraving puts a "u" shape on the inside of jacket ..even with what I would call over spun bullets like a .825 6mm have worked very well in 8 twists, even though I wouldn't recommend it...Vinegar and jackets are as you said a bad combination about the best if you really have to wash is acetone..

 

[fyrewall]

Not being into the exacting world of BR shooting, I usually get 8 twist 6mm barrels; I really liked the 105 Amax and now I am working to recover from paying about $35 for a box of 105 ELDM 6mm bullets. Having lots of 87 VMax bullets that measure about .9 inches, less plastic tip, I also shoot these at up to close to 3400 fps out of a 8 twist 6mm AI and they are satisfactory for field shooting of varmints including small rodents.

I also have a .308 that I use with stubby 110 Vmax bullets at 3200 with a 10 twist - shoots good - almost one hole with 5 @ 100. Data for that same bullet is provided for the .300 Win, 10 twist, with up to 80 grains of powder @ 3700 - brute speed! Hardly correct twist rates but somehow everything remains intact, apparently the jacket does not get ripped away from the core.

I am fearful of acetone - explosive, and bad stuff to get on skin and breathe. I have some ideas of how some folks that used large amounts of that stuff went off to an early end.

I think somehow that sticking bullet jackets to cores might be some type of fix for the bullet blow up problem.

 

[geo.ulrich]

you have to include the plastic tip in equation for stabilization rate so 8 twist in 6mm really isn't to far off. I would like to see a small amount of tin added to cores and then try and find a way to speed up galvanic process either with low heat or electrically. remember all blow ups are not only jacket related...