Whizzin Match! What's the "Optimal" BHN to...

[Old Ironsights]

run between 1200 & 1800 (1500 av) and still upset without leading?

I did the obligatory search and didn't see an answer.

My last batch of ACWW (16bhn) at 1800 hardly upsets at all, but it doesn't lead either.

I'm kinda thinking around 9 or so (2/1? ww-pb) for pistol/carbine bullets.

Thoughts? Better blends? (Nomex suit on...)

[jhalcott]

http://www.lasc.us/CastBulletNotes.htm
I think a mix of 50/50 WW/pure will give you expansion in revolvers and carbines as low as 1200FPS. Accuracy may go away as velocity increases though. You do not give much info on particular firearm or lube used. Neither was the intended target named, a ground hog or deer MIGHT require less toughness than a bear or BOAR!

[405]

Don't know about upset at terminal end but for obturation?? for accurate shooting--- I've found that if the bullet fits the gun right and the bore is good then in carbine/handgun type loads a BHN of about 8-9 with plainbase bullets will work when velocities are kept below about 1000 fps. For stouter rifle loads with velocities between about 1000 and 1500 I've settled on a BHN of about 10 using gas checked bullets. I use pure lead mixed with some alloy I have that is in various unknown ingots that range from BHN 12 to about 22. I assume it is mixtures of everything from old wheelweights to type metal. It's old enough I haven't noticed any zinc or other odd stuff. Just been adding the various harder ingots to large smelting pot of pure lead until I hit the BHN I want. Then pour ingots of the known BHN and mark them for future use. Also I add a smidge of tin for good measure to each batch.

Over time I've found that the exact % of antimony and tin doesn't matter as much as the BHN.

I've also found that by using a gas check bullet for the faster rifle type loads I can get top accuracy with a slightly softer BHN. Slightly higher BHN required for plainbase bullets. Seems that as I go up to about 1500 fps the plainbase bullets even with the 10 BHN alloy start to go inaccurate. By gas checking a comparable bullet of 10 BHN I can maintain top accuracy to around 1500 fps +/-.

I shoot mostly older originals and have no use for going to higher pressures and velocities so have no experience in the land of high cast bullet velocity (2000 fps plus).

Leading is always a nuisance. I've found that BHN is less related to leading than correct bullet fit and condition of bore at least within the velocities I shoot- less than 1600 fps.

Also, for the BPCR type loads I am pretty much convinced there is nearly full obturation of the paper patched bullets I shoot. I use pure lead at 5-6 BHN with weights from 400-520 gr for paper patch. My bores are nominal at .450 with grooves at .458. My final patched diameter is .454. I think that all or nearly all the bullet shank obturates to full groove diameter in these loads. The velocities range from 1100 to about 1350 fps.

[runfiverun]

to keep the bhn up and the alloy low for mush try 1-1 ww's and pure then water drop them you get both hard and smooshy without brittleness.

[EOD3]

Lyman #49 guesstimates an ideal rifle bullet as BNH 15.

IMHO, the "best" brew is going to change with every barrel.

[S.R.Custom]

I always seem to draw the ire of the masses when I say this, but since you asked... If you have to rely on bullet upset/obturation to provide accuracy, there is something dimensionally incorrect with the weapon that should be addressed.

That said, I use water quenched wheelweight and NRA 50/50 for everything. (BHN in the neighborhood of 18-22) It's accurate, doesn't get beat up on feed ramps or in magazines, keeps the casting process simple, and if there is a leading and/or accuracy problem, I know it's not an alloy problem. With that hardness, I can push PB slugs from my SuperMags at 40KPSI/1500 FPS without leading. Any faster or higher pressure than that, and I'm using a gas check.

Now if the topic shifts to terminal performance, then the picture changes significantly. If I'm looking for bullet expansion, then more likely than not you'll find me using jacketed bullets... [smilie=1:

[Old Ironsights]

My bad... Runfiverun got my question right. I wasn't talking/worried about obturation/accuracy - no problems there, just want optimal "mushrooming" without leading...

So, I have 1 vote for 1:1 vs my guess at 3:1...

[runfiverun]

at 3-1 you start to have no antimony in the mix as ww's generally have only 3% in them to start.
when you add some tin to the mix to replace the fill out you get from antimony you start to have a higher sn content then sb content which is problematic.

[Springfield]

I've never noticed antimony to help fill-out any. Adding high antimony alloy just made the bullets harder, never helped casting. But then I usually do BP bullets, I just need fill-out, not hardness. 1 part pure to 2 parts wheelweights gets me my Brinnell 10-11 bullets. Works in my BP guns, my wifes smokeless cowboy guns and works well in my 45 Autos. Don't do any high power rifle bullets at this time. With some problematic bullets sometimes I add a bit of tin for better fill-out, but not much. I used to get some terrible leading in some of my 45 Autos using hard cast commercial bullets. Now with my softer home cast I rarely get any. Hard bullets for general use are highly over-rated.

[SciFiJim]

One of the bits of casting lore that I picked up somewhere is that you should not exceed the percentage of antimony with the percentage of tin, but never found out why. Can someone explain why?

[Old Ironsights]

at 3-1 you start to have no antimony in the mix as ww's generally have only 3% in them to start.
when you add some tin to the mix to replace the fill out you get from antimony you start to have a higher sn content then sb content which is problematic.
?

Seems you would have more antimony than with a 1:1 mix...

[runfiverun]

tin likes lead but it loooves antimony if you have more tin then antimony available the extra tin will tear away from it and not have time to rebond with the cooling lead which will leave hard spots of tin surrounded with soft spots of pure lead.
O.I. you must have meant 3 part ww's to 1 part pure.
i was thinking 3 parts pure to one ww's,sorry.
the part about using the mixed and water dropping come in so the outer bhn would be enough for up to 2,000 fps but still retain a soft alloy.
kinda a win - win situation here as you can push it and still have alloy strength to stop it from beiing a brittle alloy.

[Old Ironsights]

the generalized rule: amount of upset mostly depends on the following two variables- *BHN & velocity*

That's what I'm trying to get at. I shoot .357 almost exclusively. Velocities range from 1000fps (snubby) to 1800fps (carbine). I want somthing that will mush well without leading, but retain weight. Assume Gas Checks.

Like I said, my ACWW C358180RF at 1800 do not mush at all on whitetails... or bags of cat litter for that matter.

[Old Ironsights]

tin likes lead but it loooves antimony if you have more tin then antimony available the extra tin will tear away from it and not have time to rebond with the cooling lead which will leave hard spots of tin surrounded with soft spots of pure lead.
O.I. you must have meant 3 part ww's to 1 part pure.
i was thinking 3 parts pure to one ww's,sorry.
the part about using the mixed and water dropping come in so the outer bhn would be enough for up to 2,000 fps but still retain a soft alloy.
kinda a win - win situation here as you can push it and still have alloy strength to stop it from beiing a brittle alloy.

May have to go that route. Got LOTS of pb... not quite 50% of my stock, but close...

[Bret4207]

What are you using for a test medium? Cat Litter? Boolit alloy is strange. It'll expand, sometimes depending on alloy and boolit design, in stuff that you wouldn't think would make it expand and vice versa. This time I'll say I think Veral has the right idea, at least as far as wound channels go. Take a gander at his book and see what he thinks if you have access. Beyond that see if you can find something other than bags of cat litter, new or used (!!!!!), to test on. Woodchucks work, so does roadkill if you have access. Cattle carcasses work great.

I've gotten significant mushrooming of round nose, straight ACWW at 1500 fps on carcasses. But they hit bone too. If you want to insure expansion, have you considered having your mould HP'd?

[45r]

Take your air-cooled WW boolits and drill a hole about .125 deep and you will get a mushroomed boolit.Putting a piece of tin foil between the mold blocks lined up about .125 deep works also.

[HORNET]

IIRC, Bullshop used to recommend a minimum impact velocity of 100XBHN for expansion based on his testing. YMMV. There was also a sticky by Grumpy One that recommends keeping the Sb and Sn contents around 3% for optimum results without becoming brittle. Once again, YMMV and a big meplat and/or HP can make a big difference. As soft as you can go with acceptable leading and accuracy is good but may require lots of testing..

[waksupi]

I recall a formula, I believe was from the old Aimoo board.
10 bn - 1200fps
11 bn - 1300fps
12 bn - 1400fps
13 bn - 1500 fps

Get the drift? 200 fps per hardness point.