BPCR and 10BHN antimony-lead alloy.

[flynth]

Hi,

I wasn't sure if this should go in the alloys forum or BPCR forum. I decided on BPCR as it is more relevant here. There was a similar thread some years ago I found via google, but it was wheel weights specific so I decided to open this one to get people's opinions.

I read in few places that one should avoid antimony in their black powder cartridge boolits because antimony "leads the bore with black powder", but I nhaven't actually observed this with properly sized boolits. With tin prices as they are and after reading opinions of the mountain molds owner that antimony alloys supposedly are easier to cast reliably I decided to give them a try. I had few ingots I bought long time ago that were around BHN 20 and they were supposed to contain only antimony and lead. I added 30% of them and the rest of lead to create an alloy that is around BHN 10. That alloy cast really well and didn't form any dross during an hour long casting session. I only had time to shoot 10 of the resulting boolits, but I haven't noticed any leading and accuracy was pretty good.

I'm planning to do a better comparison between the 1:20 alloy and this BHN 10 antimony alloy in few weeks. In the meantime I wanted to ask the forum if anyone knows where did this opinion originate that antimony leads the bore and is there any truth to it?

[Bad Ass Wallace]

In the quantity required to get an alloy of BN 10 there would only be a poofteenth of FA of antimony anyway. I use a 1:40 mix to get good casting and finish properties.

[GregLaROCHE]

I’ve never heard about such problems. I do agree that with that BHN, there’s probably not that much antimony in your final alloy. Tell us what you are shooting. Long gun or handgun. Rifled or smooth bore.

[flynth]

I’ve never heard about such problems. I do agree that with that BHN, there’s probably not that much antimony in your final alloy. Tell us what you are shooting. Long gun or handgun. Rifled or smooth bore.

I'm estimating around 5% antimony (for the pure lead hardness of 5BHN and each percent of antimony adding 0.92 BHN). I'm shooting a 45-90 Pedersoli Sharps, 32 inch barrel with tapered rifling starting at 450 bore, 458 groove tapering down to the muzzle to 446 bore, 454 groove . I'm sizing the boolits to 458 because my mold throws them at 0.4585. I haven't seen any leading in 10 that I shot already(I know it is only 10. Unfortunately I had no time to shoot more yet).

I'm considering ordering more of the high antimony alloy to mix with my lead to end up with more of that BHN 10 alloy, so I thought I'll ask people's opinions as I read in "Preparation of Match Ammunition For Black Powder Cartridge Rifles" that statement "antimony alloys lead the bore with black powder". I also read similar opinions in few other places online. It sounded like it may be a commonly held opinion in the community so I wondered if there is any truth to it.

I attach a photo of two boolits from the same mold. The one on the left is an antimony alloy, the one on the right is 1:20 tin-lead alloy(no antimony). They both look good

[Bent Ramrod]

I’ve never noticed any leading in BPCR rifles, shot with black powder, using Lino/wheelweight range scrap, except in one instance, where I shot some Money boolits while blowtubing on a 107-degree day. When I went to wiping between shots, the leading disappeared with this boolit. Those shallow lube grooves don’t leave any extra in the bore to soften fouling.

This supposes a boolit diameter that seals the bore and doesn’t allow gas cutting.

Where I find wheelweight-type antimony alloys to be problematic is when I try to cast them in custom moulds. Such moulds seem to be rated for the flow and solidification characteristics of lead/tin alloys. A prolonged casting session, unless temperature and cadence are rigidly monitored, results in the alloy flowing into the vent lines, sticking in spots along the parting of the blocks. These bits of metal are very hard to remove, and they serve to stick and tear off metal from the lands on the boolit as it is removed from the mould. So I save the junk alloys for the production moulds and, to the extent possible, use tin/lead or pewter/lead mixtures only in the custom ones.

But if you don’t see this situation, I would say you are good to go.

[country gent]

I think 5% antimony will bring you closer to 12 13 bhn. I normally shoot 20-1 over BP in my rifles. Some advocate small amounts of antimony to retard / reduce nose slumping also. I feel fit and lube are at least as important as hardness in this endeavor. Another is a to hard tough bullet may not obturate to seal the bore as well as it should under lighter loads making fit even more important. You really see this with bore riding paper patched bullets that don't seal if the bore.

In the end test see what works for you and your rifle. This is what matters.

[Lead pot]

If one figures 5% antimony of a pot full of 16# lead 1#tin makes a very hard bullet. I use a mix of 18# pure lead and one 1 pound roll of no lead solder that it 95% tin 5% antimony. This will hold the ogive setback very well where the patch ends right at the transition of the shank and ogive meets. This will also work for a GG as well.
below is an example of what a 1/20 tin/lead bullet will look like shot from a .44-100 Sharps with a 90 grain load of 2F the PP bullets has a alloy mix of what I mentioned above. It holds the nose very well with very little setback. The setback is from the bullet expanding in the chamber and throat not from nose setback.
The dimple is where the ogive and shank meets
Attachment 244652Attachment 244653

[Bad Ass Wallace]

Flynth,

Been shooting Pedersoli rifles for over 20 years, and never encountered the barrel dimensions that you quote? The barrels are made 0.450/0.458 and rifled true and finally a tapered reamer is used to impart a taper to the RIFLING so the barrel finishes 0.4515/0.458 at the chamber and 0.450/0.458 at the breech. I use a 545gn PGT boolit, designed by the late Dick Trent RIP, with a bore riding nose that accounts for the Pedersoli taper.

My casting pot holds 70lbs of alloy comprised of 65 lb of pure lead, 2 lbs of Linotype metal, and 3 lbs of 50/50 solder to arrive at a 1:40 mix. To duplicate this alloy, I firstly cast several boolits with the pure lead and weigh them (546.4gns ave) then add the alloy, cast some more and weigh them; they should weigh 545.2gns. For ever and a day, you can always duplicate this mix by weighing them.

BTW, I have a 38/55 Hiwall and an 1886 lever that also have the progressive depth rifling. Only the muzzle loading rifles by Pedersoli have parallel bores with straight non-tapered rifling.



https://www.bpcr.net/site_docs-resul...procedures.htm

There is no doubt that this combination is very accurate



Even the "Big Fifty" shoots well with 0.512 boolits

[flynth]

Flynth,

Been shooting Pedersoli rifles for over 20 years, and never encountered the barrel dimensions that you quote? The barrels are made 0.450/0.458 and rifled true and finally a tapered reamer is used to impart a taper to the RIFLING so the barrel finishes 0.4515/0.458 at the chamber and 0.450/0.458 at the breech. I use a 545gn PGT boolit, designed by the late Dick Trent RIP, with a bore riding nose that accounts for the Pedersoli taper.

Looks like I made a mistake in my measurements. I repeated the measurements and the dimensions are exactly as you said 454~455/458 at the chamber, and 450/458 at the muzzle. Thanks for pointing this out. I would've never bothered to check this again. My Pedersoli is an odd one, it is made specially for Polish market (due to our gun laws making this model obtainable with no paperwork - you can mail order it basically). It is a replica of so called 1874 'A' series with 45 - 2.4 cartridge barrel and percussion action. Allegedly rifles like this were made by the original Sharps factory when requested to people who wanted to reload brass cartridges but for some reason they preferred percussion caps to primers. One can use this rifle with black powder only in normal 45-90 brass with the primer pocket filled with a brass disk with a tiny flash hole, or with a tiny check valve you can see on my photos. Opinions on historic accuracy of the ball valve ammunition vary For those that want to maintain historic accuracy brass with tiny flash hole is also available.



For me this rifle combines my enthusiasm for black powder with the added benefit of using cartridges while still being legal with no paperwork where I live.

My casting pot holds 70lbs of alloy comprised of 65 lb of pure lead, 2 lbs of Linotype metal, and 3 lbs of 50/50 solder to arrive at a 1:40 mix. To duplicate this alloy, I firstly cast several boolits with the pure lead and weigh them (546.4gns ave) then add the alloy, cast some more and weigh them; they should weigh 545.2gns. For ever and a day, you can always duplicate this mix by weighing them.

That is interesting. I calculated your alloy contains 2.25% tin and 0.3% antimony and if we say pure lead is BHN 5, this alloy may be somewhere near BHN 6. This is pretty soft, but looking at your targets it certainly works very well for you. Can I ask what is your favourite load for your Pedersoli Sharps?

[Bad Ass Wallace]

My 45/90 started as a 45/70 and I had my gunsmith cut a precision chamber with a slightly shorter leade than the standard chamber. I load 77gns Wano 2P card wad, pure beeswax wad, under the hand lubed but unsized PGT Bullet.

Lately, I've been working with the Lyman tapered boolits which just fit into the case and basically breech seat the boolit into the rifling. You can fit 75gnd Wano 2p under the tapered boolit making it near equivilant load to the 45/90.

[17nut]

Alloying pure antimony with pure lead is but impossible and the antimony will constantly float to the top during casting.
Now tin on the other hand will readily alloy with lead and it will "alloy" (coat is a better term) with antimony and bring the other two together in a tertiary alloy.

There is no such thing as to hard alloy (for BP) if you have a proper fitting bullet and said bullet will fit in the case in the chamber!
But if you have an old rifle that depends on bullet bumping up to size then you're up a certain creek withpout a paddle.

Please do read: http://www.lasc.us/Fryxell_Book_Contents.htm

[Lead pot]

Lead is sort of a lubricant. Try soldering two fittings together using pure lead you will find that it just does not give you satisfaction.
Shooting pure lead bullets you will find very little lead in the bore and it cleans out easy. Just shoot some old shotgun shells loaded with out a shot cup now used, just wads.
It's the tin in the alloy that does the dirty work smearing the bore. You can get the alloy too hot and the bullets will look like galvanized tin. That galvanized look is the tin or tin antimony coming to the surface giving it a galvanized look and that is what will smear the bore if your lube is not doing its job.

[Lead pot]

I swaged them for my 52 S&W master and they shot great for bullseye matches. I also gave them a try for the .40-70 Sharps and they will put 10 cutting at 100 yards.

Attachment 244746