How much Build-up from Lead?

[jameslovesjammie]

When I cleaned the barrels, you seen build up in the rifling in the first 1/2" in both barrels. From that point forward the barrel was normal.

I think the bullet is too hard and not obturating until 1/2" into the barrel. Does this sound like a possibility?

Sounds like a hard bullet skidding before finally biting to me.  If you were to continue shooting, the buildup would stretch farther down the barrel, and the leading in the chamber would get "ironed" in, and be a royal pain to remove.

I know people are sick of hearing me say it, but harder isn't always better when shooting lead bullets.  You WANT some deformation.  A smaller diameter bullet will even bump up in diameter, softness allowing.  When the bullet hits the rifling, the nose of the bullet is slowed down while the base is still maintaining the same speed.  Since the rear of the bullet is catching up to the nose, the bullet will get shorter, hence "fatter" as it blocks the bore.  This blocking is called obduration (think "ob" as in "ob"struction)  Since the gas from the burning powder wants to travel in the area of least resistance, it is easier to push this obstruction out the bore than it is to go through the hardened steel that is the sides of the barrel. 

If the obstruction fits tightly...gas cannot escape past.  But if the bullet is too hard, it resists obduration.  If it is too hard and too small it will resist deformation, and since the path of least resistance is on the sides of the bullet, it will blast gas past the sides of the bullet.  This causes decreased accuracy and leading. 

If it is the right size but too hard, the bullet resists conforming to the shape of the lands and grooves.  This is what makes it "skid" across the rifling; the bullet doesn't want to deform, but the gas says, "You're going down the barrel."  Once an agreement is made between the bullet, rifling, and gas...the barrel is sealed, the the bullet quits skidding, and fits the barrel.  That is why the leading stops after a short while...because bullets that fit your barrel and conform to the rifling don't lead.

Your barrel sounds like it has "skid marks" to me.

[Riptide439]

Right On JLJ! This makes perfect sense.
Glad I only bought 1 box of the BHN21! What hardness do yo recommend?

[jameslovesjammie]

12-15 are really the hardest you need.  Good luck finding any commercial cast at those numbers, though.  Commercial casters use harder alloys because they don't want to hear from customers who receive bullets with dings and dents in them.

As far as the 21 BHN bullets...that is about what Linotype runs.  There really isn't any reason to run bullets that hard in a handgun.  This alloy is what guys use (with a gas check) to run cast rifle bullets about 2,200 fps.

[Riptide439]

The hardness of Linotype depends on the ratio of tin, antimony and lead.  I use a ratio of  2% tin, 6% antimony and 92% lead. This gives the material a brinell rating of 16. Upping the antimony to over 10% will give you brinell ratings of over 20. A hardness rating of 16 is perfect for all of my cast needs. 

So what would the brinell rating be if antimony was 8% and lead was 90%?

[jameslovesjammie]

So what would the brinell rating be if antimony was 8% and lead was 90%?

I would assume the other 2 percent is tin, since that much antimony will make the alloy brittle.  The tin will reduce the surface tension of the melt and will give you better fill out of the mould.

90-8-2 would be close to the old Hardball alloy, which is 90.25-7.5-2.25.  I would imagine 16-18ish.

[Riptide439]

The other 2% was Tin. Not yet ready to dive into making my own - but I haven't ruled it out! 
the 90% - 8% - 2% is the lowest commercial boolit I have found so far that uses Carnauba red lube since this sounds like it is cleaner than the blue lube. Is this correct?

[jameslovesjammie]

The other 2% was Tin. Not yet ready to dive into making my own - but I haven't ruled it out! 
the 90% - 8% - 2% is the lowest commercial boolit I have found so far that uses Carnauba red lube since this sounds like it is cleaner than the blue lube. Is this correct?

I like Carnauba Red.  It's what I personally use.  The blue lube could be a number of different lubes: Thompson Blue Angel, Magma Lube, LBT Blue, etc.  Most commercial lubes are very hard and wax based.  These do a great job of being able to be shipped across the countryand have the lube stay in the lube grooves and be less sticky/tacky.  Are they the best lube for shooting?  Not necessarily.  Softer lubes will usually do a better job.  Carnauba Red is the hardest lube that White Label Lube makes, but it is still softer than most other commercial lubes.  It has been shot past 2,700 fps in a .30-06 with no leading.

I absolutely believe that Carnauba Red is a better lube than any of the other commercial lubes.  But that doesn't mean that you will necessarily have bad results from someone using a different lube. 

[papaairbear]

When I cleaned the barrels, you seen build up in the rifling in the first 1/2" in both barrels. From that point forward the barrel was normal.

I think the bullet is too hard and not obturating until 1/2" into the barrel. Does this sound like a possibility?

Sounds like a hard bullet skidding before finally biting to me.  If you were to continue shooting, the buildup would stretch farther down the barrel, and the leading in the chamber would get "ironed" in, and be a royal pain to remove.

I have a question on this, if I may.  Would using a bullet .002" oversized with a reduced powder load compensate for this?  I've ordered some Dardas .45 at .452 because my barrel slugged .451.  BHN is 17, IIRC, for the Dardas bullets.

Think I found the answer:  http://castboolits.gunloads.com/showthread.php?110213-From-Ingot-to-Target-A-Cast-Bullet-Guide-for-Handgunners

[Riptide439]

amonr - Is this Chemistry 101 or 201? 

[photobiker]

Lead build up.  What are you looking for?  How do you know if you are depositing lead in the barrel?  In pistol rounds I tend to keep the velocities down so I don't think there is a problem.  But I have a rifle I'm struggling with, old surplus.  Plated are pretty accurate but I'm struggling with lead.  They are all over the place.  So I thought I would start increasing the velocities to see if accuracy improves but I'm looking for that point of leading because of excessive velocities.

[jameslovesjammie]

My lube of choice is Lyman's Super Moly.

Another GREAT lube for handgun velocities!  It is just a little too "sticky" for some folks, but it does a great job of what a lube needs to do.  Another great lube in the "sticky" category is the old NRA 50/50 (50% beeswax and 50% alox.)

Commercial bullet makers tend to use harder wax blends in their bullets than home bullet casters.  The reason is so that when they ship them, the lube stays in the grooves.  If the bullets are transported in the back of a semi-truck, the temperatures in the summer time can exceed 120 degrees and a soft lube will melt off the bullets.  When the customer opens their box, they have naked bullets and the bottom of the box is coated in lube.  To keep happy customers, they use a lube with a higher melting point.

Carnauba Red requires a heater be used on a luber-sizer when applying it.  It will not flow unless the temperature is elevated.  That makes it a little more of a pain in the butt to apply, but it will stay in the lube grooves once cooled.  As soon as I run out of Carnauba Red, I have an order of BAC to run in my sizer.  It is a mixture of Carnauba Red and 50/50, so it will flow without heat in my Star sizer and still give the excellent lubricating/sealing/seasoning properties of 50/50.

[jameslovesjammie]

amonr - Is this Alchemy 101 or 201?   

Fixed it for ya!

[jameslovesjammie]

Lead build up.  What are you looking for?  How do you know if you are depositing lead in the barrel?  In pistol rounds I tend to keep the velocities down so I don't think there is a problem.  But I have a rifle I'm struggling with, old surplus.  Plated are pretty accurate but I'm struggling with lead.  They are all over the place.  So I thought I would start increasing the velocities to see if accuracy improves but I'm looking for that point of leading because of excessive velocities.

This should really be a thread on its own.  Lots of additional information needed.

[jameslovesjammie]

None of the above. I believe it is categorized as the "Art and Science of Reloading".
The beauty of reloading is that you can make it as complex or simple as you like. However it pays
to have background knowledge on the recipes you want to construct. Some people bake cakes from a pre-mix box, some from scratch. 

What a great way to put it!

[Riptide439]

amonr - Is this Alchemy 101 or 201?   

Fixed it for ya!

Thanks jlj. Its been quite a while since school! 

jlj, actually you are killing me! Since you posted your smelting thread, all I see next to my barbeque is a 20lb tank that will melt lead!