Cast boolits in a 4(T)

[dromia]

Joe's "Cast Bullets For Beginner And Expert SECOND EDITION, 2007". Is a good compilation of theory and practice, much of it sourced from Cast Boolits. As a compilation its not a good read but still has a lot of info to dip into. Some of which is now outdated but such is the nature of the beast.

Joe used to make the "Book" available on CD, he may still do, so all the calculators an spread sheets worked.

He sent me a few copies, I'll see if I can find them.

[dromia]

The LASC site also hosts Glen Fryxels articles which are also a good read for cast boolit afficinados. His theories on lube function cause everlasting discussion and disagreement that sometimes leads to virtual blows. :lol:

[Sandgroper]

The LASC site also hosts Glen Fryxels articles which are also a good read for cast boolit afficinados. His theories on lube function cause everlasting discussion and disagreement that sometimes leads to virtual blows. :lol:

I've read some of his articles and found them very interesting, but I'm not sure that I fully understand the need for boolit lube as jacketed bullets aren't lubricated, but cast boolits are. He makes sense in describing the lube a seal to prevent gas cutting (http://www.lasc.us/FryxellLubeCastBullets.htm), but he doesn't mention lubes such as liquid alox. As a newbie to cast boolits I'm sure it's all necessary, but I can't fathom why. :? -but night shift at the moment might not be helping. :)

[Ovenpaa]

I would like to think I was a reasonably accomplished reloader however cast boolits is a whole new and exciting world to me (Always good to learn something new) So I am also curious about the use of lube with cast.

[Alpha1]

What does bullet lube do?

In summary, bullet lube is pumped from the lube groove to the barrel surface by compression, linear acceleration and radial acceleration. In addition, lube is injected forward during the firing process, as the result of high-pressure gas leakage into the lube groove. This injection process forms a floating fluid gasket around the bullet, and serves to limit gas cutting and is a kind of ballistic stop-leak

[dromia]

The LASC site also hosts Glen Fryxels articles which are also a good read for cast boolit afficinados. His theories on lube function cause everlasting discussion and disagreement that sometimes leads to virtual blows. :lol:

I've read some of his articles and found them very interesting, but I'm not sure that I fully understand the need for boolit lube as jacketed bullets aren't lubricated, but cast boolits are. He makes sense in describing the lube a seal to prevent gas cutting (http://www.lasc.us/FryxellLubeCastBullets.htm), but he doesn't mention lubes such as liquid alox. As a newbie to cast boolits I'm sure it's all necessary, but I can't fathom why. :? -but night shift at the moment might not be helping. :)

Jacketed bullets are lubricated lead boolits, the copper in the jacket act as a lubricant of sorts its different properties leaving coppering which is less of an issue than leading. Jacketed bullets have also been lubricated over the years with various greases and slickums. Currently molybdenum disulphide being back in vogue.

See my next post for my views on gas cutting.

[dromia]

What does bullet lube do?

In summary, bullet lube is pumped from the lube groove to the barrel surface by compression, linear acceleration and radial acceleration. In addition, lube is injected forward during the firing process, as the result of high-pressure gas leakage into the lube groove. This injection process forms a floating fluid gasket around the bullet, and serves to limit gas cutting and is a kind of ballistic stop-leak

Possibly Dave possibly, at the end of the day the performance lube of lube is really dependant on bullet fit and alloy hardness/elasticity. Get good boolit fit and you don't need boolit lube. Whitworth proved this with his hexagonally rifled muzzle loader, but then his forte was being able to measure and work to extremely tight tolerances so boolit fit was well within his capabilities. His contribution to the modern industrial society is vast. Also there are people currently shooting unlubed boolits with mixed success in getting that perfect boolit fit and a properly smoothed barrel.

Lube does what it says on the tin methinks, it leaves a film of lubricant in the barrel which helps reduce friction at the boolit/barrel interface and therefore reduce leading. However with a poorly fitting boolit no amount of lube will compensate for that. Leading in itself is not necessarly a bad thing its the build up of leading that causes problems, see bore conditioning.

Gas cutting, well I'm not sure about that. I've retrieved many shot cast boolits over the years, as have many others, and never seen any gas cutting especially on the base, the temperature spike is there for so short a time that it doesn't seem to melt the lead.

However I suppose that it could have an effect on thin moulding flashings on the base and the lube grooves. With poor boolit fit when the gases over take the boolit then you could get gas cutting of these lead slivers and the type of melted on leading associated with gas cutting. This type of melted on leading could also come from the heat working on lead already left in the barrel from friction.

So in reality with a properly fitting boolit gas cutting/leakage should not be an issue, the whole purpose of seeking good boolit fit is to ensure that the boolit is a perfect as possible when it leaves the barrel so as to make the most of its accuracy potential.

The other role for lube and lube grooves, as I see it, is in helping the boolit maintain its integrity at the moment of firing. The inertia of the boolit means that the base starts moving before front of the boolit causing what is known as "bump up" and this is said to help seal the bore. The Minie boolit is a classic example of this. This bump up can also cause boolit deformation at the nose know as "boolit slump" this is very common in bore riding designs that don't fit the bore.

So what the lube in the lube groove does is act as a sort of shock absorber (haven't got the right word here) that helps the boollit keep its shape and length (BC) as it compresses under the acceleration.

An example of this property comes when sizing boolits down a lot say 0.319" to 0.314". If you do this with an unlubed boolit the lead smears into the lube grooves and can end up a right mess, however if you fill the lube grooves first and then resize the boolit keeps its intergrity albeit with some lengthening depending on the mount of compression needed to push the boolit through the die.

So given proper boolit fit I think the lube performs two functions, it lubricates (fills the pores of the bore, cast boolit barrels need to be seasoned with each lube before you will get top accuracy) the barrel to reduce friction leading and secondly it helps maintain boolit integrity during acceleration in the barrel.

That is in relation to smokeless cartridges, in black powder cartidges it also performs a third function of helping to keep the fouling soft and is often added as grease cookies to supplement the lube in the grooves.

At the end of the day the function of boolit lube is still speculative and one of the reasons for that is it is very difficult for us lay experimeters to get replicable situations for boolit fit, alloy strength, barrel condition, loading, measurement etc etc etc. So as to be able to build up a robust body of empirical data to be able to draw absolute conclusions from.

What I am certain of is if you want to get the the best from your lube then boolit fit is key.

I am also certain that if the want to get the best from any boolit/bullet then boolit/bullet fit is king.

But what would I know.

No doubt there will be questions now about lube types as Sandgroper has alluded to in his reference to Xlox/liquid alox, but b****r that for now as I'm off to shoot cast boolits on a 25yrd range using a Pedersoli Sharps 1874 Quigely rifle chambered in 45-90, could you do that easily and cheaply with you copper condom curios? :lol:

[Alpha1]

The only problem I have had with cast boolits
(we wont mention the mauser thing Adam) is sights most of my reloading is for milsurps with iron sights.
The sights are calibrated against full metal jacket factory ammo so you have to re calibrate your sights to the cast re loads you are using.Never had any problems with accuracy.

[dromia]

What Mauser was that Dave? :lol:

Mums the word mate; mums the word.

[Ovenpaa]

Mauser??