bullet casting.

[Randy Bohannon]

Lead tin alloys age soften over time before stabilising.

http://www.lasc.us/Fryxell_Book_Chap...Metallurgy.htm



I've been casting some hollowpoint bullets, massive hollowpoints, with recylced air rifle pellet lead and they are too soft.

The nose section collapses as I put them through the lubrisizer.

I have some pure lead and some linotype and so think some experimentation is in order.

[thibben]

Enfield2B,

lead tin alloys do not to any degree change over time, at least the rations I use for BPCR's, between 16:1 for PP and 20:1 by weight for canuallared/GG bullets (but just starting to play with PP)

But the OP was talking Linotype,which has antimony and tin, all be it more antimony that tin.

If you look up articles by Dan Theodore you will find some good info. Bottom line if alloying lead, tin and antimony is never have more tin that antimony, (here you go, for some info: http://www.shilohrifle.com/forums/viewtopic.php?t=24564 )

Re. wheel weights - concur, that is why I said 'old wheel weights', zinc has no real place in cast 'boolits' IMHO

Brgds Terry

[Randy Bohannon]

Tin/Lead alloys do age soften, they stablise after a while but that does not mean they do not age soften from just cast.

Lead-tin (Pb-Sn). Which metals do we add to lead to make better bullet metal and why? The first and most obvious need here is to make the alloy harder, but there are other factors that play into this answer as well. Historically, tin was used because it was readily available in pure form, mixed easily with molten lead and contributed desirable properties to both the molten and solidified alloy (castability and hardness, respectively). Tin also increases the hardness of the alloy but does not interfere with the malleability of lead (a key point that we‘ll return to). Tin lowers the viscosity and surface tension of the molten alloy, allowing it to fill out the mould more effectively, resulting in a higher quality bullet. Tin is limited in its ability to harden lead, achieving a maximum hardness of about 16 BHN at 40% tin.

These binary lead-tin alloys undergo slight to moderate age softening upon storage (1-2 BHN units), with the harder alloys undergoing more of a change than the softer alloys. The hardness of a binary lead-tin alloy generally stabilizes after about 2-3 weeks.

Heat treating binary lead-tin alloys does not provide any change in hardness. At typical lead pot temperatures, lead and tin are infinitely miscible with one another, at the eutectic temperature (361 F) tin is still soluble to the tune of 19%, but at room temperature tin is still soluble in lead at the 2% level, meaning that as the bullet cools down there is significant precipitation of a tin-rich solid solution in the form of granules and needles in a matrix of lead-rich solid solution.

[thibben]

RB,

Concur, which is why I said 'lead tin alloys do not to any degree change over time' as not many folks cast bullets and shoot them the next day (well I don't) and if you look at the link I posted you will see Dan T's results for the alloys I listed, 20 & 16:1, after 2 or 3 days 'that's it' they do not change.

I have found this to be accurate by measuring the harness of both bullets before loading , which could be months after casting, and pre mixed ingots , which could be many months after smelting (I premix quite a few kg using commercially pure lead and tin). FYI I use the Cabin Tree tester (see here: http://www.texas-mac.com/Evaluations...s_Testers.html ) which is now made by this bunch: http://cowboybullets.com/Lead-Tester_p_57.html

Brgds

Terry

[Randy Bohannon]

RB,

Concur, which is why I said 'lead tin alloys do not to any degree change over time' as not many folks cast bullets and shoot them the next day (well I don't) and if you look at the link I posted you will see Dan T's results for the alloys I listed, 20 & 16:1, after 2 or 3 days 'that's it' they do not change.

I have found this to be accurate by measuring the harness of both bullets before loading , which could be months after casting, and pre mixed ingots , which could be many months after smelting (I premix quite a few kg using commercially pure lead and tin). FYI I use the Cabin Tree tester (see here: http://www.texas-mac.com/Evaluations...s_Testers.html ) which is now made by this bunch: http://cowboybullets.com/Lead-Tester_p_57.html

Brgds

Terry

Very interesting, thank you.

I like that Cabin tree tester very much, particularly as it seems to be able to measure run out as well...

[thibben]

RB,

Bit off topic but what do you 'shoot'? I'm assuming BPCR as ML and gallery do not require that much 'fineness' (no slur intended, just an observation!)

T

[Randy Bohannon]

I have obtained a Milhec copy of a H&G 30 cal mould that produces something called the "Ness Glanceproof (or) Safety" bullet: http://castboolits.gunloads.com/show...e-proof-boolit

It has a hollowpoint which is almost .200 wide at the mouth and as deep as the bottom lube groove and is designed to come apart completely, minimising the chance of significant pass through and ricochet.
The hollow portion is the part which is getting squashed by the nose punch of the luberisizer and hence my need for a stronger alloy.

I suspect antimony might be the way forward to promote fragmentation.

[tacfoley]

RB,

Bit off topic but what do you 'shoot'? I'm assuming BPCR as ML and gallery do not require that much 'fineness' (no slur intended, just an observation!)

T

BPCR is shot out to 1200 yards.

Muzzle loading matches are also out to 1200 yards.

I weigh my bullets to within 2gr, even though they weigh either 405gr or 535gr. I try and make them them very best I can within my limitations.

I don't shoot gallery, so I can't comment on it.

tac

[enfield2band]

Enfield2B,

lead tin alloys do not to any degree change over time, at least the rations I use for BPCR's, between 16:1 for PP and 20:1 by weight for canuallared/GG bullets (but just starting to play with PP)

But the OP was talking Linotype,which has antimony and tin, all be it more antimony that tin.

If you look up articles by Dan Theodore you will find some good info. Bottom line if alloying lead, tin and antimony is never have more tin that antimony, (here you go, for some info: http://www.shilohrifle.com/forums/viewtopic.php?t=24564 )

Re. wheel weights - concur, that is why I said 'old wheel weights', zinc has no real place in cast 'boolits' IMHO

Brgds Terry

Thanks for the link it is interesting.

The method I use to measure lead hardness seems to work close enough for bullet casting.

Randy:- Lead airgun pellets measure out the same as lead waterpipe on the drop test.

[Randy Bohannon]

So almost pure lead then Enfield?

[thibben]

RB

that is an interesting looking bullet!

re the nose deformation by the lubrisizer top punch, if you have a spare top punch put a piece of tank repair putty into it and push it down on the bullet, you end up with a custom top punch. I do this for all my bullet molds, Real shame to cast up a nice prolate bullet to have it look like a bulldog after lubing!

T

[loiner1965]

RB

that is an interesting looking bullet!

re the nose deformation by the lubrisizer top punch, if you have a spare top punch put a piece of tank repair putty into it and push it down on the bullet, you end up with a custom top punch. I do this for all my bullet molds, Real shame to cast up a nice prolate bullet to have it look like a bulldog after lubing!

T

good tip.....i have a lee hardness tester if anyone wishes to borrow

[enfield2band]

So almost pure lead then Enfield?

Its seems to be. Either is suitable for Minnie bullets.

[tim56]

Many Thanks to all for the info. Finally settled on a 25 / 75 mix of linotype / pure lead. A scratch test compared to a commercial bullet
seams to be about the same. They drop out of the mold at .431" ish so have bought a new .429" sizing die which arrived yesterday and
I'm hoping to get some rounds made up for next weekend. Tally Ho.! Tim

[Randy Bohannon]

Hope you don’t mind me posting this on your thread Tim?

today I tried a 10%linotype to 90% lead alloy for both the hollowpoints and the Lee 180 gr RN moulds.

i had initially tried 100% lead ( or near as damn it) and it proved far too soft to go through the lubrisizer without the nose section squishing down, I the case of the hollowpoint to 0.325”!.

A harder alloy is then needed to avoid deformation and so the 10/90 link/lead was tried.

This alloy cast very well and was a little harder than the pure lead meaning the lee 180 bullets came out ok but the hollowpoints still squished out.

I think this is to do with the gas check which being copper needs more force to size than a pure lead boost would.