Antimony , how abrasive?

[spurgon]

I have heard several times that antimony is abrasive in regard to use in cast bullets. This must be minimal since most everyone tells me that wheel weights are the standard alloy to use for casting. What's the scoop?
spurgon

[Lloyd Smale]

if you can wear a barrel out using ww bullets id like to shake your hand as either you shoot alot more then i do or i feel sorry for you as you probably only own one gun. I dont think in the average shooters lifetime your ever going to wear out a barrel shooting any alloy of lead.

[Shiloh]

Antimony alloys with the lead just as the tin and trace amounts of arsenic does. The abrasive qualities of antimony (if any) would certainly be greatly diminished by the other alloys.

As the previous post says: I dont think in the average shooters lifetime your ever going to wear out a barrel shooting any alloy of lead.

Shiloh :castmine:

[WKAYE]

I dont think in the average shooters lifetime your ever going to wear out a barrel shooting any alloy of lead.

Depends on what you're going to do. High antimony alloys (eg. monotype @ 19%) erode a throat very quickly. Shooting the 55gr RCBS cast of mono @ 2750 FPS in a 12" twist 223 erodes the throat about .100 " every 1000 rounds. This is exactly the same as my 8" twist target rifles shooting 80gr Bergers with "balls to the wall' loads of H322. The toughest barrels I have used are Lothar Walther SS and they last little more than 3000-3500 rounds. :Fire:

[Shiloh]

Depends on what you're going to do. High antimony alloys (eg. monotype @ 19%) erode a throat very quickly. Shooting the 55gr RCBS cast of mono @ 2750 FPS in a 12" twist 223 erodes the throat about .100 " every 1000 rounds. :Fire:

Why would you want to shoot straight monotype?? Could it not be alloyed down to Lyman #2 alloy or just used to sweeten wheelweight alloy?? Straight Monotype bullets would be very brittle and un-necessarily hard wouldn't they??

Shiloh :castmine:

[Bass Ackward]

I have heard several times that antimony is abrasive in regard to use in cast bullets. This must be minimal since most everyone tells me that wheel weights are the standard alloy to use for casting. What's the scoop?
spurgon


It is. Antimony comes in little metal rocks with spines. Many oldtimers would not shoot antimony period. This is why you hear so much about 40-1, 20-1 and 16-1 mixes. These had no antimony. But these were the softer barrels that you can't shoot jacketed in either.

And what it does, depends on what you do to it. How much pressure you put it under. How hard of bullets that you like to shoot. Much like sand paper. Push real light on sand paper and it won't cut as well as if you put a lot of force. If you are shooting pretty close to bore, it will do a lot less than if you are choking say .003. It will slow in polishing once the pressure lowers.

One Redhawk I have had a .4295 bore new that went to .430 after 2500 rounds and just slugged this week @ .4305 about 4000 rounds. Land height was .419 new and now is .423. So it will clean up and then pretty much stop unless powder roughs up an area like a forcing cone. Powder roughs it up and lead polishes the rough away.

Antimony is a lot less abrasive when countered with equal amounts of tin alla Lyman #2. It's also a lot less abrasive when used with a good lubricating lube too. If you want to smooth up a barrel pretty quick, use antimony, hard bullets, and LLA. That'll polisher up quick.

[Maven]

"The keyword for babbit is high antimony composition." ... felix

Two questions about Sb's abrasiveness: First, if it's so abrasive, why is it used as a bearing metal? Second, for WKaye, how do you know it's the monotype that's eroding your throat and not the hot powder gases needed to push the CB to 2,750fps? Inquiring minds want to know?

[WKAYE]

Shiloh,

Good accuracy at high velocity. Brittle ? Haven't noticed that. Works well on varmints.
I enjoy playing with different alloys and in the 22 centerfires I've found straight Monotype works the best. I believe Tom Gray also used it to set all his BR records . 30 Cal ? Anyway I have about 600 lbs of it and I like to play.


Maven,

Yes there's antimony in babbitt , usually with enough tin to surround the antimony crystals. Saw guide Babbitt has the highest concentration of antimony @ 19%, with 9% tin. Exactly the same as Monotype. The most common around here is #7 :10% tin 15% antimony. Being a Lobster fisherman , I know that if I don't keep my Babbitt shaft bearing well greased it certainly will chew the SS shaft.

Not having a lab , I guess I can't really prove that Monotype erodes throats any worse than say WW. Most 22 centerfires will move the throat ahead around .100 in the first 1000 rounds. That's just the freshly cut sharp edges being worn away. After this inital wear , mild loads and light bullets drasticly reduces the amount a throat lenghtens . Depending on the rifle, I use between 19 and 21 gr of H4895 in the 223 with 55gr alloy bullets. With jacketed bullets this would be a very mild load and past experience tells me that barrel would last a very long time . Like I said before, about 3000 rounds with Monotype and it's cooked. That's still a lot of shooting at crows and to show the boys how lead really can shoot well.

[Maven]

WKAYE, I've also experienced throat erosion in my .243Win. after years of shooting ~3,000fps loads with jacketed bullets. Fortunately, the bbl. is not yet "toast."

[Bass Ackward]

WKAYE, I've also experienced throat erosion in my .243Win. after years of shooting ~3,000fps loads with jacketed bullets. Fortunately, the bbl. is not yet "toast."


Paul,

That's why I used the handgun example. Hard to separate the powder wear from actual wear of lead. But I again mention Dan of Mountain Molds experience. When he started with his 30-06 Remington he used .311 bullets. 1000 rounds later he was filling the throat with .318.

Powder wear is normally thought to lengthen a throat. Diameter wear I would attribute to obturating lead.

[WKAYE]

Dear Mr Ackward :-D ,
You just pointed out an error I made in my previous posts , one that I often correct my friends on. The erosion I was refering to was actually in the leade. :oops: I haven't seen the amount of throat erosion you refer to. My 22 bullets are sized to .226 and slip into a fired case , so I doubt they are completely filling the throats of the factory chambers. I use much softer alloys in the larger bores.