Bullet core stripping

[J. Valentine]

You are right about using pure lead wire to make cores. I have never been able to buy wire that way so the 99.5-.5 lead/antimony is what I buy. Bruno last time I bought had some 100 % stuff and some guy snapped it up before I could ask.
You are also right that some of the bullet making Posts are coming out of some book or somebodys fishing tackle box. I might be right on about bullet making I might be wrong but I want to stay a Poster on the inside here not a reader on the outside so I will refrain from some comments. Jerry Thornbrugh says hi.

Stephen Perry
Angeles BR

Thats correct , It is very hard to actually buy 100% PURE lead but most core wire is very close.
Most hand swagers will small presse or reloading type presses will use a lead with a Brinell hardness of about 5 -6
Bigger dedicated swaging presses can use a hardness up to about 8 or 10.
Hydraulic presses can swage right up to annealed copper.
Thats the problem here we have people with all different kinds of presses and dies giving advice that is not qualified to a particular system.
Of course you can make good bullets with harder core materials but that harder material might wreck another persons gear.

 

[J. Valentine]

Guys, let's try to come up with some new ideas; some new way to bond cores and jackets so the bullets are absolutely immune to core stripping. By 'bonding' I don't mean securing the core and jacket to prevent separation in game so as to retain maximum weight; no, I'm thinking only in terms of locking core and jacket to prevent core slip during initial spin-up.

I have already told you about my 'Heat treatment idea.' What a fiasco.

Many bullet makers use some type of etching on the cores before seating, others boil them in some type of detergent or phosphate. At this time, I feel the best method is to simply insure the jackets and cores are squeaky clean by washing them in a triple bath of NuTri or Trichlorethane, but I'm always looking for ways to improve on this.

Have you ever considered the use of rosin? Could we make up a thin "Dip" using pure rosin dissolved in a suitable thinner such as MEK, acetone, toluene or such, dip the clean, dry cores in this solution, then pour them out on a clean surface to dry? Would there be anything better than rosin? What do you think? Worth a try?

Gene Beggs

A cure for an unproven problem?
It is a fact that greasy or dirty cores and jackets are not good for accuracy but many millions of good accurate bullets have been made with 99% pure lead cores and just a good solvent degrease , washing and drying of both , Some people age their cores until a slight white corrosion appears.

If core slippage is really a problem then why? oh why? do corebonded bullets not shoot better than unbonded bullets on average. (I actually know why.)
If I make identicle 308 projectiles one corebonded and the other unbonded the unbonded one shoots the best groups.
I am not trying to put down Gene's ideas . I am trying to understand where this alleged core slippage is causing a problem.
I dont belive that Mr Vaughn is correct about this rotational inertia causing core slippage as a bullet exits the muzzel because I believe that the whole mass of the bullet would be spinning as one mass by the time it exits the barrel. Providing the bullet is properly made . At the point where the bullet enters the rifling there COULD be some inertial stress on the jacket core junction . However I theorise that it would be all over and settled down by the time the bullet exits.
I think Mr Vaughn may have been grasping for answers to explain bullet blow up which can be caused by a whole set of other circumstances . Some of which do involve thin jackets and deep rifling , rough barrels , heating of the bullet etc.
Berger is working on it now.
It is theoretically possible for a poorly made bullet with a poorly seated core
fired under mild pressure circumstances in a generous size bore to have a loose core on exit from the muzzel . However it would not be accurate and may not even make it to the target .
Conversely a very tight bore can swage down a projectile and on exit the jacket springs out and loosens the core.

 

[bryan]

Gene.........Bonding

Gene, I see what you are getting at. At this point in time, etching the cores is about the only option available for a Benchrest quality bullet. I'm sure there are glues out there that would help bond the core to the jacket, but remember this..........ANY substance you try to cram into the jacket with the core has to be able to move and re-distribute itself evenly, or there will be an imballance in the bullet. That's a NO-NO.
Same reason a too hard core won't fill the voids and causes an imballance.
Same reason (here I'm gonna take it in the shorts) having some lube left on a core will create a pocket and cause an imballance condition.
I really don't think the lubricity of a bit of resuidal lube causes the problem as much as the light spot in the bullet CREATED by the lube does. A bullet made this way has to shake like a dog pooping razer blades!
Over the years, I've pondered this problem and I too, have abused the wife's oven, stuck my fingers together with super glue and came up on the loosing end of the stick each time.
It is my opinion that the only way to ensure jacket to core adhesion is to etch the inside of the jacket, as well as the outside of the core. After all, the interface of the jacket inside and core outside is what is at stake here. Ammonia would work, but evenly distributed application would be a problem, and the bullets would then be taken to a way higher level of "hand made". Plus the fact that you would not want any of the etching process to reach the outside of the jacket.
Even a turn of a brush inside the jacket would produce a rough surface that would help the core and jacket adhere better, but I don't know of anyone that wants to take the time to do that to each individual jacket. Bullet prices would skyrocket!
This being said, I'm as concerned about bullet integrity as anyone, but I really don't think core slippage has cost anyone a win in short range benchrest........we just don't shoot them as fast or in such a fast twist barrel to cause a problem.
Bryan

 

[Gene Beggs]

You can't take a too large core and "press fit" it into a jacket with any success. The process is called "swaging up".......in other words, the core seating process EXPANDS the jacket, and the core seated jacket, ready to point form is smaller than the finished bullet. The final process of point forming expands the jacket a bit more to the final dimension.
Think of the jacket as that half empty toothpaste tube that has been squeezed in the middle, then you start rolling it up from the bottom........the rest of the tube expands (this assumes you have the cap on tight)
To give a little more insite, suppose you have a bullet that is 6mm and you want to make it a .22, like necking down a case. You could squeeze it down in the die, but the spring-back of the copper jacket would work in reverse and it would spring back towards it's original size and the core would quite possibly rattle in the jacket.
The only time a bullet component is reduced in size is when the core itself is squirted to a specific size. From there on out, everything expands.
Copice?
Bryan

Thank you Bryan, very well stated.

 

[Gene Beggs]

I have a new idea. How bout we wrap each core in a baby condom before we core seat them. That should seal the core better in the jacket and when you lose a shot out of a group you could say the condom leaked.

a.k.a. known as a bad date gone wrong or a family secret nobody is supposed to know.

Stephen Perry
Angeles BR

Steve, that's an idea and will be taken under advisement.

 

[Gene Beggs]

Guys, don't misunderstand; I'm not saying core stripping is running rampant among the benchrest crowd but I do believe it happens more often than most would believe.

We have all experienced the odd lot of bullets that just would not shoot, no matter what we did. We change to another bullet and the same rifle immediately begins to put 'em in one hole. Could it possibly be the bullet maker let his single bucket of core washing solvent get a little dirty and the last batch of cores wound up with a thin coating of lubricant on them which compromised the interface between cores and jackets?

Or,,, is it possible the bullet maker got in a new lot of jackets that were perfect in every way except for the fact they were slightly softer than the previous batch and he failed to adjust the core seater die to compensate?

J. Valentine, you understand all this perfectly and obviously, you make fine bullets. I would imagine the chances of your bullets experiencing core stripping is close to zero, but not everyone is as skilled and knowledgeable. If there was an easy way to insure a good bond between core and jacket without everything having to be perfect, I believe it would improve the aggs.

J-4/Berger jackets are about as perfect as anything can be. Many shooters have good bullet making equipment and usually make very good bullets but once in a while they have trouble because they do not completely understand the finer points of what we are discussing here. What we need is a little insurance; something that will make core seating less critical and insure a good bond between core and jacket.

BTW, you said you knew why bonded bullets did not shoot as well as others. Would you share that with us, please.

Gene Beggs

 

[243winxb]

Vapor blasted bullet jacket Olin Corporation (Stamford, CT)

Vapor blasted bullet jacket Document Type and Number:United States Patent 4660263
Abstract: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 http://www.freepatentsonline.com/4660263.html

A solution to the core-jacket separation problem is achieved by the present invention which provides a method of roughening the inside of bullet jackets by internally vapor blasting bullet jacket in a special support die to reduce relative slip between the resultant bullet jacket and its core. A pressure relief orifice us preferably put in the bullet jacket base and supporting jig to give improved vapor blasting by allowing the vapor blasting media to exit without accumulating in the jacket.

This would seem to keep the core from spinning in the jacket. Not sure it would apply to Benchrest. I am sure i am the last one to know of it.

 

[J. Valentine]

My feeing on your bonded/un-bonded cores in bullets is that the cores weight if bonded would act like a gyroscope tiliting the bullet in flight back and forth. Better to let a un-bonded core do it's thing inside a jacket and let the bullet as a whole stabilize as it move towards it's target.

Stephen Perry
Angeles BR

That is pretty much the problem. No matter how perfectly you try to bond a bullet slight inaccuracies cause imbalance . Also a bonded bullet does not obturate ( expand) to seal the bore the same as an unbonded bullet does.

The different ways to bond a bullet all have these common problems to some degree.

With chemical bonding you have the problem of perfect glue dispersion and the possibillity of uneven bonding .
With solder bonding you have the problem of potentail imbalance due to the need to core seat after melting the core material and possibly air pockets or flux pockets within the core and shrinkage . I dont know for sure .
Thorough melting is required .
For the home swager solder bonding is still the most practical and with care will produce a good game bullet.

 

[Bob Kingsbury]

About lead wire, 99% pure being good-------No way
I purchased a roll of lead wire once, actually another fellow and I
split a small pallet. While cutting cores, I found chips of steel
in the wire. No doubt I was happy to find it there and not in my
squirt die.
One more thing, it can be found in Harry Popes writing that
he once rifled a barrel with coarse emory only and had no bullet
slippage.
I for one am having problems with this and wonder
how .150 groups turn into .250's because the core slipped.

 

[J. Valentine]

Vapor blasted bullet jacket Document Type and Number:United States Patent 4660263
Abstract: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 http://www.freepatentsonline.com/4660263.html This would seem to keep the core from spinning in the jacket. Not sure it would apply to Benchrest. I am sure i am the last one to know of it.

What you are seeing here is a shortcut fix for a mass production problem.
It may allow them to ignore the need to have perfectly clean cores and jackets.
They use transfer presses that feed core wire down to the bullet jackets and just chop it off at the desired length. Then the core is swaged and seated in one punch stroke. The press is running at warp factor 3 and the core wire is straight off the roll. The jackets are straight out of the box.
The factory is a factory and is like an Idaho dust bowl.
When the guy running the press needs to take a leak he pisses in the lubricant hopper . You get the picture.

This does not compare to what home BR bullet makers are doing. I certainly hope.
However it does indicate that people have been thinking about ways to make a bullet core grip better . Exactly what Gene is talking about.
I can see the need in certain mass production situations but its the need in custom hand swaging that is evading me at the moment.

 

[J. Valentine]

About lead wire, 99% pure being good-------No way
I purchased a roll of lead wire once, actually another fellow and I
split a small pallet. While cutting cores, I found chips of steel
in the wire. No doubt I was happy to find it there and not in my
squirt die.
One more thing, it can be found in Harry Popes writing that
he once rifled a barrel with coarse emory only and had no bullet
slippage.
I for one am having problems with this and wonder
how .150 groups turn into .250's because the core slipped.

An impurity in the core wire has nothing to do with the suitability of the metal composition as a melt. It just means dirty manufacturing techniques and poor quality control.

How did you determin that you are having core slippage problems?

 

[Gene Beggs]

Progress Report,,

Well,, at this point in the discussion most experienced bullet makers agree; pure lead is best for making cores. If antimony is used it should not exceed one half of one percent.

There is also agreement on the importance of thoroughly cleaning cores and jackets to remove all traces of lube before core seating.

Opinions diverge on the subject of etching jackets and cores. Some believe cores should be oxidized by boiling in dishwashing powder and letting them dry on a clean surface before core seating. Some recommend etching jacket ID's with vinegar before core seating.

Many, including myself, feel the best grip between jacket and core is achieved by thoroughly washing and drying both jackets and cores. Then seating cores with a proper fitting punch with the core seater die adjusted to the optimum setting; not to soft and not too hard.

Although some dismiss the idea that core stripping is a problem, all agree on the importance of proper core seating before pointing up.

Does anyone have anything else to add before we move on to the next subject? Jacket hardness/annealing.

Later,

Gene Beggs

 

[Pete Wass]

My thinking was perhaps

You can't take a too large core and "press fit" it into a jacket with any success. The process is called "swaging up".......in other words, the core seating process EXPANDS the jacket, and the core seated jacket, ready to point form is smaller than the finished bullet. The final process of point forming expands the jacket a bit more to the final dimension.
Think of the jacket as that half empty toothpaste tube that has been squeezed in the middle, then you start rolling it up from the bottom........the rest of the tube expands (this assumes you have the cap on tight)
To give a little more insite, suppose you have a bullet that is 6mm and you want to make it a .22, like necking down a case. You could squeeze it down in the die, but the spring-back of the copper jacket would work in reverse and it would spring back towards it's original size and the core would quite possibly rattle in the jacket.
The only time a bullet component is reduced in size is when the core itself is squirted to a specific size. From there on out, everything expands.
Copice?
Bryan

a tenth or two, not a very big difference. Wouldn't take a very big difference but I've never dealt with this kind of thing so have no sense ( lots will agree ) of how fragile jackets are.

 

[Bob Kingsbury]

J Valentine

I think you have missed my point.
If the manufacturer of the lead wire can't keep the steel chips out of his
wire, how can I have confidence that the melt is clean. For that
matter how do I know I found the only chips in the wire. Some small one may have made it into the cores.
I have no fliers that I want to attribute to core slippage.
Not convinced this problem exists, but we will find a cure for it.

 

[J. Valentine]

Well,, at this point in the discussion most experienced bullet makers agree; pure lead is best for making cores. If antimony is used it should not exceed one half of one percent.

There is also agreement on the importance of thoroughly cleaning cores and jackets to remove all traces of lube before core seating.

Opinions diverge on the subject of etching jackets and cores. Some believe cores should be oxidized by boiling in dishwashing powder and letting them dry on a clean surface before core seating. Some recommend etching jacket ID's with vinegar before core seating.

Many, including myself, feel the best grip between jacket and core is achieved by thoroughly washing and drying both jackets and cores. Then seating cores with a proper fitting punch with the core seater die adjusted to the optimum setting; not to soft and not too hard.

Although some dismiss the idea that core stripping is a problem, all agree on the importance of proper core seating before pointing up.

Does anyone have anything else to add before we move on to the next subject? Jacket hardness/annealing.

Later,

Gene Beggs

I would like to add.
First off , 99.?% pure lead is the best to use in light built presses that are only capable of using it . That does not mean that only pure lead makes an accurate bullet.
Harder alloys in heavier presses will still make accurate bullets.
However I think that the alloy can be too hard for certain bore pressures and poor obturation can become an issue. Where that point is I dont know.
I have seen some quite accurate Barns x bullets and they are very hard in comparison although not BR accuracy.
So I stay with what has always worked , 99.9 percent pure lead or a Bhn hardness of 5-6.

 

[J. Valentine]

I think you have missed my point.
If the manufacturer of the lead wire can't keep the steel chips out of his
wire, how can I have confidence that the melt is clean. For that
matter how do I know I found the only chips in the wire. Some small one may have made it into the cores.
I have no fliers that I want to attribute to core slippage.
Not convinced this problem exists, but we will find a cure for it.

No, you said " About lead wire, 99% pure being good-------No way "

The alloy percentage has nothing to do with good quality manufacturing.
Your comment says that 99% pure lead is " no good " .
That gives people the impression that the previous posters are not correct.
The only thing that is not good is the unfortunate fact that you have some impurities in your core wire and you have a " Pallet " of it.

That situation has absolutely nothing to do with the suitability of 99% pure lead in general for making bullets that other people have purchased .
Its only your lead wire that is crook.

You seem to have taken a reversal of statement concerning core slippage.

Anyway lets not turn this thread into an argument because it has the potential to turn into some realy good information on the subject of bullet making . I must commend Gene Beggs for his sensible stewardship of this thread . I have great respect for him and have learnt a lot from his posts in the past.

 

[K Hope]

Poor Quality Control

Bob

Lead suppliers are not usually in the bullet business however, they still should be following a standard and be able to back it up with documentation. Even with pure lead if the process is off so could the CG be off.

Ken

 

[alinwa]

Bob

Lead suppliers are not usually in the bullet business however, they still should be following a standard and be able to back it up with documentation. Even with pure lead if the process is off so could the CG be off.

Ken

Ken,

Are you saying that molten lead varies in density? Or that density varies as hardness? I'm just curious, I have no idea....


al

 

[J. Valentine]

Hopefuly the impurities are only in the first few feet of the spool he started using.
I would cut a foot off wire off all the rolls and test half off that.
If other rolls show contamination then I would want it all replaced .
Keep the 6 inch samples as proof of the contamination.
If they dont replace it and the contamination continues through the whole batch or part of the batch then you may be better off melting the bad rolls down fluxing off the impurities and casting the cores.
Double swage the cast cores and they will make good bullets.

 

[J. Valentine]

Ken,

Are you saying that molten lead varies in density? Or that density varies as hardness? I'm just curious, I have no idea....


al

I think he is saying that an impurity in the lead core can upset the center of gravity .